FT8 Operating Guide  
Weak signal HF DXing for technophiles  
by Gary Hinson ZL2iFB Version 2.37  
FT8 Operating Guide  
FT8 Operating Guide  
Recent changes to this document (just the  
stuff)  
Version  
Date  
Changes made  
2
2
2
.37  
.36  
.35  
Sept 2021 New chapter about logging (tnx for the inspiration Joe W4JF).  
June 2021 Tips on working a fox (tnx Ned AA7A).  
Mar 2021 Noted JTsync (thanks Gust ON6KE). New front graphic, courtesy of Club Log.  
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FT8 Operating Guide  
1
Introduction and purpose of this document  
1
1
1
.1  
I started compiling these notes back in July 2017 in the  
course of making over 50,000 FT8 QSOs on the HF bands,  
learning how to drive the software by using it. Some tips  
were inspired by suggestions from other FT8 users and by  
the WSJT-X developers on the WSJT-X reflector (worth  
joining). Many address Frequently Asked Questions and  
draw on my 40-odd years of HF DXing … some very odd.  
Some of my tips (such as split  
operating, tail-ending and using  
low power) are contentious and  
not universally adopted by FT8  
users – and that’s fine. To an  
extent, we are figuring this stuff  
out for ourselves as we go along,  
which for me is all part of the fun.  
These tips work for me. Your  
situation and preferences may  
.2  
.3  
That said, these are just tips, pragmatic suggestions aimed  
at making FT8 easier and more effective to use on the HF  
bands. They are not rules or laws! It’s only a hobby! The  
digital modes, protocols and programs are being actively  
developed, while the operating conventions or habits on-  
air are still evolving. Other approaches may be even better me know if they work better. ꢀ  
than those I suggest here … and that’s cool.  
vary.  
By all means try out  
different approaches … and do let  
In particular, I must point out that I am a keen HF  
DXer with zero experience using FT8 intentionally  
for meteor/rain/aircraft scatter, EME, topband and  
VLF, 6m and up etc. I have only used FT8 on 80  
through 10 metres. Hopefully much of the advice  
here is useful in other contexts (e.g. topband  
DXing) but different techniques may well be  
appropriate and necessary, in which case please  
I am primarily a Microsoft Windows  
sufferer user. WSJT-X is an impressive  
example of multi-platform coding that  
works on Linux, MacOS, Windows (XP and  
up) and other platforms, with only minor  
differences … but since I only run it on  
Windows 8.1, please don’t pelt me with  
rotten tomatoes if things don’t quite work  
look elsewhere for guidance. Likewise for other  
modes such as JT9 and MSK144.  
as described on your system.  
RTFM! Seriously, please study the docs! The FT8 software installation instructions, online user guide,  
built-in help and tooltip popups will help you install, configure and start using the software with your  
computer and rig. Most initial issues, problems and queries are answered therein, plus there are  
useful tips. This “Operating Guide” is intended to help you get the best out of FT8 from an  
operational perspective after you have it up and running. If you still have issues after all that, please  
search the online support forum (reflector) archives  and finally feel free to ask for help on the  
reflector. The developers are focused on designing, developing and refining the protocols so please  
have some consideration: basic queries answered elsewhere are likely to remain unanswered.  
Important disclaimer  
We are all individually responsible and indeed accountable for complying with our  
licenses plus applicable laws, regulations and conventions that may, for instance,  
specify permitted powers, modes, bands/frequencies (e.g. on 60m) and bandwidths,  
or impose obligations concerning remote operation, on-air identification and logging.  
Just because the software allows us to do something does not necessarily mean it is  
legal and appropriate for us to do so. Neither the development teams, nor the author  
of this guide, are responsible for your compliance. You are, dear reader!  
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FT8 Operating Guide  
2
START HERE  
2
.1  
Use the latest available release of the FT8 software. You have a few program choices:  
WSJT-X was written by the team that invented the mode (the daddies, you might say!). In the  
best tradition of amateur radio, WSJT-X is open-source, hence others are developing variants  
(
derivatives) of the program, changing the user interface and in some cases meddling with the  
JTDX by Igor UA3DJY and team is a stable, usable variant with several helpful tweaks to the user  
interface. It is similar enough to be familiar to anyone who already knows WSJT-X. Although  
sadly the official JTDX documentation is woefully out of date, see Appendix D for tips on using  
The user interface in MSHV by Christo LZ1HV is a little different. MSHV enables semi-rare DX  
stations to make several QSOs in parallel using the regular FT8 protocol (not fox-n-hounds  
DXpedition mode  more hunt saboteur mode) … at the cost of increased transmit bandwidth  
higher band occupancy) and less power per signal. The multi-QSO facility does not work in  
contest mode (thankfully!) and should not be used in the normal FT8 sub-bands, please.  
JS8call by Jordan KN4CRD is a derivative that re-purposes the core FT8 digital transmission  
protocol to enable longer free-text messages to be exchanged. This allows a more  
conversational style of QSOs at the same leisurely rate of about 5 words per minute. As with  
plain FT8 and in contrast to CW, RTTY and PSK, messages are sent blockwise as heavily-  
compressed messages, not as individual characters. IT REMINDS ME OF TELEX <STOP> Or  
Twitter. Or simplex traffic handling <OVER>  
Logging programs (such as Logger32 and N1MM+) can interface to FT8 programs, effectively  
using them as intelligent soft modems. Maybe one day the loggers will take over the  
sequencing, highlighting etc. leaving just the message coding and decoding to the modems, but  
for now the programs interface to share tasks such as logging completed QSOs.  
2
.2  
Software updates are frequent with all variants as bugs  
and flaws are discovered and fixed, and new functions  
Aside from ‘alpha’, ‘beta’ and  
production’ there are other,  
roughly equivalent terms. WSJT-X  
are released for alpha or beta testing.  
If  
imperfect/incomplete software makes your blood boil,  
give FT8 a wide  
has its ‘Release Candidates’ and  
General Availability’ versions. JTDX  
It’s worth checking from time  
to time for new versions of the  
berth and keep your  
cool. If you prefer  
uses ‘Evaluation versions’, ‘Step  
releases’ and ‘General releases’.  
software and this guide. Make  
reasonably stable  
it part of your routine e.g. at  
and reliable software, stick with the production releases,  
avoiding the betas and definitely the alphas.  
the start of the month, and/or  
keep an eye on social media.  
Please, read it. Study it. Ingest it. Memorize it.  
Banish dumb questions! Be like FT8 boss!  
This advice stands even if you use JTDX.  
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FT8 Operating Guide  
2
2
.3  
.4  
With your chosen software running, press F1 and study the help file/manual. The WSJT-X help is  
well written, if I say so myself. You’ll discover, for instance, that the confusing combinations of  
shift, alt or control keys and clicks are handily explained on the screen by pressing F5 to “Display  
special mouse commands”. By far the most useful combination in WSJT-X is to shift-click on the  
waterfall to put your transmitted signal there (think of it as ‘shift my Tx). If nothing else sticks  
from these notes, at least remember to shift-click … or right click in JTDX.  
Although not yet shown on the pop-up help, we can also right-click on the WSJT-X waterfall and  
1
then click the only option to set both Rx and Tx frequencies right there .  
From time to time, check for  
updates to the digimode software,  
as you should for all the other  
software on your system. Most  
applications, operating systems  
and drivers are updated or  
patched occasionally, addressing  
bugs and flaws or adding new  
facilities (potentially including  
changes to the FT8 protocol itself).  
WSJT-X does not automate this for  
New releases are  
reflector and the news soon  
percolates through other ham  
radio forums, plus on-air of course.  
It’s much the same with JTDX and  
MSHV: join the online communities or monitor the authors’ websites to keep up with  
developments.  
1
Why we can’t simply left-click to move the Rx and right-click to move the Tx in WSJT-X is beyond me. Much more intuitive …  
and that approach works perfectly well in JTDX.  
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FT8 Operating Guide  
3
Important: accurate timing  
3
.1  
Check your computer’s clock. Accurate timing is quite  
important for FT8: if your computer clock is wrong by more  
than a second or so, you will probably experience problems  
e.g. few responses to your CQs and being ignored whenever  
you call others.  
If you see plenty of FT8  
signals on the waterfall but  
few decodes, blobs that cross  
the horizontal tramlines on  
the waterfall and/or a distinct  
bias in the DT values on the  
decode, those are all strong  
clues that your computer’s  
clock may need resetting.  
Note: despite what some may claim, extreme millisecond  
accuracy is NOT required. FT8 signals contain distinctive  
synchronisation sequences that the receiving systems use to  
identify the data portions in the received audio stream.  
Accuracy to within a second is plenty good enough in practice.  
If your computer is Internet-connected, it’s easy to check the clock by browsing to the Time.is  
3
.2  
JTDX displays a rolling average of the DT values (delta time i.e. how many seconds each message  
is offset relative to the expected start and finish times according to the system clock) and two Lag  
values (i.e. how many seconds into  
the start of the next period it took  
your computer to decode the  
messages shown, followed by the  
count of messages decoded) in  
Band Activity header area (if wide  
enough) ►  
On a busy band, if everyone else seems to be a bit early or late, chances are that your own clock is  
wrong. An average DT value between minus 1 and plus 1 is fine in practice since JTDX can still  
decode reliably even with DT of 2 seconds (e.g. if a DX station’s clock is a second fast while your  
clock is running a second slow). If your average DT is more than ±1, adjust your clock.  
The Lag values indicate whether your computer has enough processing power. QRP computers  
struggle to decode all the messages on a busy band, especially if you have configured the software  
to dig deep into the noise for every last scrap of information. Conversely, QRO computers cope  
easily and quickly with all the signal processing required, without intruding very far (if at all) into  
the next period. So, if you see large lags and often notice late decodes appearing after you have  
started transmitting a message, it may be time to fiddle with the software settings, close down  
other programs to conserve resources for FT8, or consider upgrading your trusty old difference  
engine or steam-powered abacus to something more modern, more this-century.  
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FT8 Operating Guide  
3
.3  
Manually adjusting your system clock soon becomes annoying, trust me. There are better ways.  
For starters, pop open the computer lid and check/replace the button-cell battery that should keep  
the real time clock running even when the PC is powered down. Provided you have Internet access,  
the free Meinberg NTP software maintains clock accuracy, initially by synchronising your PC time  
to reference time servers on the Internet using Network Time Protocol designed for that purpose,  
and then micro-adjusting the clocks tick rate to remain synchronised (rather than just periodically  
resetting the clock, which is the more common but cruder approach). Install, configure, check,  
others, each with their fans.  
3
.4  
Recent versions of Windows Server and Windows 10 offer an updated W32Time time service called  
stopped, configured and queried from an elevated command prompt e.g.  
C:\> w32tm /config /update /manualpeerlist:pool.ntp.org,0x1  
where:  
/config means we are reconfiguring the W32tm Windows time service  
/update means apply the config changes to the service  
/manualpeerlist: means we want to specify NTP time servers other than the Windows default  
server time.windows.com  
pool.ntp.org tells the system to choose a nearby time server from the global pool. There are  
several regional pools (e.g. oceania.pool.ntp.org) and country pools (e.g. nz.pool.ntp.org) or  
you can name one or more specific time servers instead (separate their addresses with commas)  
,0x1 is a flag meaning use the ‘special poll interval’ for this server, where ‘special poll interval’  
is a fixed value in seconds defined in the registry under this key:  
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient  
e.g. a SpecialPollInterval of 600 decimal means poll the time server every 10 minutes.  
If you are unconcerned about the accuracy of your clock but simply want to work  
someone with timing issues, you can deliberately nudge your clock forward or  
backward manually. You may notice their blobs don’t line up with the horizontal  
timing lines on the waterfall, as in this example  YD3BGM’s messages were decoded  
OK  with an uncorrected DT of -2.4 seconds (i.e. he was transmitting 2.4 seconds  
early, relative to my computer  
clock). On the headphones, I  
heard his tones starting well  
before other stations using  
the same timeslots. First I  
called him several times without success,  
despite the path being wide open between  
us.  
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FT8 Operating Guide  
Guessing that he might be using software with less tolerance on timing, I  
clicked to open the Windows system clock  opened the change date  
and time settings function, clicked the Change date and time button,  
clicked the seconds part of the digital clock, clicked the up arrow 2 or 3  
times to advance my clock by about 2 or 3 seconds (deliberately making  
my system clock inaccurate!), then clicked OK to set the clock. After  
checking the decodes to confirm that his DT was reduced to just 0.2  
seconds, I responded to his CQ call again and this time we completed a  
QSO easily. I closed with a free-text message “CHK UR CLOCK” … which  
he evidently did a few minutes later. Meanwhile I had reset my own  
system clock until the time.is website showed it was within a second of the  
correct time. Meinberg NTP (which I simply left running throughout the  
process) adjusts the clock rate to correct it gradually from there and  
maintains millisecond accuracy until the next time I run into the same  
situation.  
Tip: to move his  
blobs up the  
waterfall, click  
the up arrow.  
3
.5  
From time to time, the FTn reflectors suffer zombie  
If you are offline (perhaps clinging  
precariously to a mountain peak on a  
SOTA expedition, or on a remote IOTA  
DXpedition), you can use a GPS  
receiver or radio time standards such  
as WWV to check and adjust the  
computer clock. Even a reasonably  
accurate quartz watch will do provided  
it was recently checked against a  
reliable time reference before you set  
out. Alternatively, simply listen to the  
FT8 signals on a lively band to figure  
out when most of them start and stop:  
that’s your cue to set your clock.  
outbreaks whenever someone naively asks what is the  
best way to set their system time, or suggests some  
other way to meddle with the time settings. GPS  
pucks, Rasperry Pies, WWV, mean(DT), clock-nudgers  
and other such ideas have all come up, repeatedly,  
been kicked around for a while before eventually  
slipping back to the graveyard … until the next  
outbreak. For all home-based hams, any suggestion  
not involving a definitive time reference is  
fundamentally unsound. Those involving atomic  
clocks may be viable  but are generally trumped by  
Use an NTP time server from the pool” if you are  
Internet-connected, or “Use GPS” if not. How to do  
that is simply a matter of personal choice. There is  
[
Thanks Rod YJ8RN for the tip]  
These modes are not designed for long conversations or ragchewing. Rather  
they concentrate on efficient exchange of such basic information as call signs,  
Maidenhead grid locators, signal reports, and acknowledgements at the  
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FT8 Operating Guide  
4
Important: transmit levels  
4
.1  
Although FT8 is a constant-carrier FSK  
mode (unlike PSK, CW and SSB),  
overdriving will distort and widen your  
signal (making it less likely to decode)  
and may generate spurii. Set the  
transmit levels so that the entire chain  
from AF generation through to RF  
transmission is operating linearly.  
Check out your transceiver, sound system and  
software on-air on a quiet frequency with a  
competent ham giving you honest feedback, or while  
monitoring your own transmissions on a Web SDR as  
you systematically adjust the settings and make  
notes. Beware, though, that web SDRs can be  
overloaded by strong signals, so don’t.  
4
.2  
If you set your transmit levels as badly as the FT8 station ringed in red on the left  you may  
unknowingly be generating ‘ghostly barcodes’ (in the 3 dotted rings): despite looking like some  
obscure new digimode, these are audio harmonics caused by generating too much audio output  
from the PC sound card which overloads the audio input circuits in the radio: [Tnx tip Bill G4WJS].  
4
4
.3  
.4  
Setting your transmit levels is a bit more complicated than it seems: simply adjusting the rig’s  
power output control is not sufficient as even QRP signals can be rotten if the rig’s audio is  
overloaded and distorted.  
Take care adjusting the audio output level from the sound  
card and audio input level to the rig: consult your radio  
manual to find out how to set the audio drive level  
properly. On some rigs, the ALC meter is, in effect, a  
distortion meter: any non-zero ALC indication is bad news.  
On rigs that use ALC to control the power output  
Sorry I can’t be more specific here.  
If you are unsure, err on the side  
of caution: keep your PC audio  
output level low, just enough  
drive to generate some RF output  
(you don’t need much!).  
(e.g. Icoms), high ALC indication is normal at QRP levels, so  
it’s not much help for setting the audio input.  
On the Elecraft K3, set the PC sound card  
output (using the sound card headphone  
level slider and/or the “Pwr” slider on the  
WSJT-X/JTDX main window) and the K3’s line  
input level (confusingly, using the front panel  
MIC” control in DATA mode) to indicate 4  
blobs on the ALC meter with a flickering fifth  
blob indicating the onset of ALC action ►  
Listen to your transmitted audio using the rig’s monitor function – maybe not all the  
time but it pays to listen occasionally just in case, for some reason, you are  
transmitting distorted audio, PC bleeps, DX announcements, wideband noise, coughs  
or whatever. Watch your power meter too for clues that something might be amiss.  
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FT8 Operating Guide  
The Spinal Tap approach, also known as Mediterranean  
Syndrome (“All knobs to 11”) will create more mayhem and  
complaints than FT8 QSOs. Resist the urge.  
With many FT8 stations using QRP, someone running,  
say, 100 watts or more stands out from the crowd …  
but not in a good way, especially if they are not hearing  
callers. Similarly, those running 50 watts to large  
beams on a wide-open band: that’s a lot more ERP than  
most FT8ers. However, QRO may well be necessary  
and appropriate on marginal paths.  
Automatically report callsigns and  
Aside from QRO being antisocial and usually reports to PSK Reporter by selecting  
unnecessary, if your signal is too strong, it may be dirty F2 Settings  Reporting  Network  
and may overload receivers and audio cards at the DX Services  Enable PSK Reporter  
end, preventing your signal from decoding reliably. Spotting. On the PSK reporter map, if  
Take your cue from the signal reports you receive: if you others receive you much stronger  
are getting positive reports, you can probably do just as than you receive them, your receive  
well (maybe even better) with a fraction of the power. capabilities need some attention,  
Remember: decibels are logarithmic. Cutting your and/or you may be running excess  
4
.5  
power in half will reduce average reports by just 3 dB;  
cut it by half again to lose another 3 dB, and so on. If  
you are receiving mostly negative  
or zero reports, you are in the  
power. [Tnx tip Martin G0HDB]  
right region. I normally adjust  
my transmit power to get  
reports between 0 and -10 dB.  
If you receive a 58 report but  
you’re not using SSB, something  
may be seriously amiss!  
4
.6  
If you are routing transmit audio  
from the sound card to the front-panel microphone input on the rig, be sure to turn off the radio’s  
speech processor and any audio shaping/profiling when using digimodes to avoid distorting your  
signal. Radios with a rear-panel line-level input especially for digimodes, or a special ‘data’ mode  
that automatically disables the processing (such as the K3), tend not to suffer issue. [Thanks for  
the tip Joe W4TV]  
Take care not to exceed your radio’s rated power output for digital modes.  
Each FT8 over lasts 15 seconds. Transmitting at 100% duty cycle for 15 seconds  
may cook your finals, especially on bands or antennas where the PA is less  
efficient. Check the radio manual for advice  seriously, read the manual.  
Listen for additional fan noise. Feel the radio case for excess heat. If you smell  
smoke, you’ll wish you had paid attention to this issue before it escaped.  
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FT8 Operating Guide  
4
.7  
Although FT8 is a weak signal mode, not a QRP mode  
per se, please keep your transmit power down. Be  
nice! Generally on HF, if a path is open, just a few  
watts will do. Put your amplifier on standby. Turn  
down the wick to QRP levels. Try it! If you don’t get  
any responses at all, try 10 watts, maybe 20 or 30. If  
you find that you routinely ‘need’ 100 watts or more,  
that is a strong hint that your feeder and antenna  
system are inefficient, or you are flogging dead bands.  
Check for corrosion and loose connectors. Try making  
a simple halfwave dipole as a comparison antenna.  
You will find that you can receive better if your  
antenna is in good shape, and  trust me  good  
reception is kinda useful for DXin.  
There are situations where QRO, up to  
your license limit, is both appropriate  
and necessary, for instance CQing on a  
closed band, hoping to catch DX as the  
band opens, or calling someone weak  
(
below, say, -20 dB). Occasionally, we  
experience one-way propagation as if  
there is giant diode in the  
a
ionosphere: DX stations are loud but  
cannot hear us. Maybe they have high  
QRM their end. Maybe there is a tilt in  
the ionosphere. Maybe they have  
badly designed or operated systems.  
4
.8  
Near the low end of the range, Signal-to-Noise Ratios  
“All SNR values from the decoder limit  
are of dubious value due to how they are calculated  down to minus infinity lie just below  
the decoder threshold and estimates  
of SNR near that threshold can have  
huge variance despite only being a  
few percent different in signal  
strength. The WSJT-X decoders limit  
these potential outlier estimates to  
an artificial floor which is known to be  
just below the lowest possible true  
The SNR figures compare the strength of the signal (50  
Hz wide in the case of FT8) to the noise across the 2½  
kHz bandwidth typical of an amateur SSB receiver:  
that’s 50 times the signal bandwidth (17 dB). So a -17  
dB SNR FT8 signal is on a par with the noise, making it  
virtually inaudible. For comparison, CW is copiable by  
SNR value achievable from the mode  
as determined by rigorous application  
of information theory.”  
[
Tnx Bill G4WJS]  
The cough gauge ►  
I also noticed by accident that when I cough  
the gauge goes up into the red.”  
Ah, that’ll be because your PC microphone is  
active. Try selecting the soundcard input from  
your rig. Or dose-up on cough syrup.  
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FT8 Operating Guide  
5
Important: receive levels  
5
.1  
The bar graph audio level meter in WSJT-X or JTDX should normally  
read about 30 dB on a dead band, increasing to about 50 dB on an  
active band with about a dozen stations QRV simultaneously, higher  
still on an HF band buzzing with life and lots of strong FT8 signals. If  
the level goes too high and turns red, you are reaching the  
compression point in your sound  
The bar graph bar should card and may be over-driving it,  
normally  
showing  
be  
green, causing distortion and sampling  
acceptable errors in the ADC (Analogue to  
The audio level bar  
levels. If it turns red, Digital Converter) that, in turn,  
there’s too much or too reduce the ability to decode FT8  
graph reminds me of  
Star Trek’s medical bay  
little received audio.  
signals. You might even damage  
your sound card.  
5
.2  
Here’s how to set the audio input level to WSJT-X or JTDX on a  
Windows system, step-by-step:  
1
2
. Right-click the Windows loudspeaker icon at the bottom right  
corner of your main screen and select Recording devices ►  
. Select the sound card input that receives audio from your radio  
(preferably a “line” input if there is one on that sound card,  
otherwise the “microphone” input) then click Properties  
3
4
. Select the Levels tab and set the slider near the middle  
of the range. Hopefully it is most linear in this region.  
Trust me, it doesn’t need to be precisely in the middle.  
. If there is a balance control, set both audio channels to  
the same level. On a radio with dual-receivers feeding  
the left and right channels on a stereo output, or with  
two radios, you may want to monitor each channel  
separately with two instances of WSJT-X or JTDX, for  
example monitoring FT8 and WSPR simultaneously.  
5
. Click OK to close the Levels tab, then  
open the Advanced tab . Check that  
the default format is 48000 Hz (DVD  
Quality), the preferred sampling rate  
for WSJT-X and JTDX. The default  
default rate is often 44100 Hz (CD  
Quality): converting that to 48000 Hz  
wastes CPU cycles, creates resampling  
errors and degrades decoding - best  
avoided if 48000 Hz is available and  
works on your system (it may not). 16  
bits are sufficient: more is OK.  
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FT8 Operating Guide  
6
7
. Click OK and OK again to exit the Windows sound settings.  
2
. Launch WSJT-X if it is not already running . With your  
Clap your hands or shout out: if  
you see the bar graph level flick  
up, you may have selected the  
PC’s microphone rather than the  
radio input! Oops. Easily done.  
radio OFF, check the bar graph at the bottom left corner  
of WSJT-X main screen. The level should be at or near  
zero, flickering red. There may be a few dBs of noise  
generated in your sound card, or a little stray pickup on  
its input (e.g. some AC hum if it is poorly shielded). If  
you see a lot of input, something is wrong. Check that you have selected the radio audio input  
to WSJT-X under F2 Settings  Audio. The input should show the sound card line or  
microphone input from the radio that you checked/adjusted above.  
8
. Now turn ON your radio and tune to a quiet  
In contrast to VHF/UHF, there are  
band, with the attenuator off, RF gain up high  
usually lots of strong FT8 signals on the  
HF bands at peak times: “weak” HF DX  
signals are generally only weak relative  
to other HF signals, rather than weak in  
absolute terms relative to the noise  
floor, so strong signal handling and  
and preamp set as normal. You should hear just  
a little background noise on the radio - band  
noise plus noise generated in the receiver  
itself. The bar graph in WSJT-X should be read  
about 30 dB. You may need to adjust the audio  
output level from the radio (the Line Out level if  
dynamic range tends to be more  
you have that facility, otherwise the AF level) and  
important than sensitivity on HF.  
until WSJT-X shows about 30 dB.  
9
. If your radio has a fixed (non-adjustable) line level output or one  
It might be worth  
comparing different  
USB ports for your  
USB sound system or  
that cannot be reduced to about 30 dB on a dead band, have you  
plugged the radio line output into the microphone socket on the  
PC sound card by mistake? Or have you selected the microphone  
input rather than the line input on the sound card? Check the  
labels on the sound card inputs and the sound card settings. If  
there is no “line in” but only a “microphone” input, and no way to  
turn off the microphone preamplifier in the sound card settings,  
you might need an external attenuator (e.g. a potentiometer) in  
rig connection: some  
are noisier than  
others in my  
experience.  
the audio lead from your radio to reduce the audio level feeding  
into your PC sound card, or you may need to use the radio’s headphone output rather than  
the line out, using the radio’s AF gain control to set the quiescent level on the WSJT-X bar  
graph to (yes, you guessed it) about 30 dB.  
1
0. Now tune to band that has some life in it, using  
If there is so much band activity that  
the band selector on the WSJT-X main  
the bar graph is near the top of the  
screen. You should hear FT8 signals on the radio  
scale and turning red, turn off the  
and see signal blobs on the waterfall. The WSJT-  
radio’s preamp, turn on the attenuator  
3
X bar graph should read about 40 to 70 dB , still  
and/or reduce the RF gain to bring the  
in the green, and after a period or two you should  
levels back down to the green zone.  
see some decodes appear.  
That’s it, you’re done! To avoid having to repeat this whole process, you might like to make some  
notes about the settings though, just in case ‘someone’ fiddles with ‘something’.  
2
If your radio has a built-in sound card and USB interface, you won’t be able to use the sound card while the radio is switched  
off  but to simulate no audio input, maybe you can tune to a dead band and disconnect your antenna? [Tnx tip VE3AND]  
3
The dB values here are decibels relative to a reference level, the digitized signal value 0001.  
Copyright © 2021 ZL2iFB  
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FT8 Operating Guide  
5
.3  
Even having set up your receive levels carefully, and if you  
are using a high quality modern rig with a high dynamic  
range, particularly strong signals often appear wider than  
others … but don’t be too quick to blame it on someone  
running excessive power and splattering. They may be  
locals, and if they are DX it could just be that the path  
happens to be wide open between you.  
When conditions are favourable,  
I’ve often seen genuine QRP DX  
signals showing plenty of red on my  
waterfall.  
Remember, FT8 is  
designed for weak signal DXing.  
The yellow fuzz either side of a solid red blob like this is probably just  
a display artifact i.e. low-level skirts on the digital filter that generates  
and colours the waterfall. Despite appearances, most FT8 signals are  
clean in fact. That said, I would avoid CQing close to a strong signal like  
this (in the fuzzies), even if I chose to  
More tips about using your  
transmit at the same time as him.  
There are generally better places elsewhere.  
filters and AGC below.  
FT8 Operating Guide  
6
Other software settings  
FT8  
FT4  
None  
3.575  
None  
7.0475  
10.14  
14.08  
JT9  
1.839  
3.572  
None  
7.078  
10.14  
14.078  
4
1.84  
6
6
6
.1  
Preferred frequencies for digimodes are normally expressed as  
VFO “dial” frequencies in megahertz, with the radio set to USB  
or DATA mode  The actual transmit frequency is higher by the  
audio frequency according to where the red Tx goalposts sit  
above the waterfall.  
3
5
7
.573  
.357  
.074  
1
1
0.136  
4.074  
.2  
.3  
Dial frequencies for various modes can be checked and  
customised through the F2 Settings  Frequencies tab. If you  
make a mess of the settings, right-click the table and select  
1
8.1  
1.074  
4.915 24.919 24.919  
8.074 28.18 28.078  
18.104 18.104  
21.14 21.078  
2
2
2
Reset’ to recall all the default frequencies for all the supported  
modes.  
In order to avoid your transmit frequency continually jumping or being pulled around by successive  
callers, in WSJT-X, select (tick, check) the Hold Tx Freq option; in JTDX, click the yellow Lockd TX=RX  
button to turn it to green Tx/Rx Split. Even with Hold Tx  
Freq or Tx/Rx Split selected, you can still put your Tx  
where you want by shift-clicking the WSJT-X waterfall or  
right-clicking the JTDX waterfall, and you can call someone  
on their frequency (simplex) if you really must: simply hold  
Ctrl as you double-click their CQ message, or shift-  
click/right-click your Tx to their frequency, or click the up-  
arrow button to move your Tx frequency. It’s seldom a  
good idea though, especially if you are calling a rare DX  
station. Their frequency tends to get busy with callers.  
6
.4  
Pick a readable font type and size under F2 Settings  
General tab, particularly for the decodes. Personally, I  
prefer sans serif fonts with a slashed zero such as Monaco  
or Consolas . Your monitors, eyes and preferences may  
vary, so fiddle with the fonts and font sizes until you’re  
happy. FT8 is an experimental mode after all!  
The watchdog (WD) timer is a vigilance  
It's not goo
control, a kind of dead-man’s handle. If  
while transmitting the operator appears to  
have dozed-off for a defined period, the  
trusty automatic watchdog springs to life,  
shutting off transmissions that would  
otherwise continue indefinitely, displaying  
a red warning message. There are two  
things you can do to stop this:  
without a break: I recommend taking a breather  
after 5 or 6 minutes max. The WD timer counts  
down in the bottom right corner of the main  
window. When the time is up and the Tx  
disables, it’s worth checking that your transmit  
frequency remains clear of QRM at the times you  
would be transmitting. In fact, it’s not a bad idea  
to QSY anyway since you may be QRMed by  
someone too weak to see (hence the lack of  
response to your CQs or calls), or perhaps  
coincidentally they have been bitten by their  
watchdog at the same moment as you!  
1
. Kick the watchdog! A click anywhere in  
the window (even between the buttons)  
tells the watchdog you are still awake and  
unexpired, resetting its countdown timer.  
4
6
0m frequencies vary around the world: check your license and local bandplan for details.  
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FT8 Operating Guide  
2
. Give yourself more time. You’ll find the starting value for the countdown under F2 Settings then  
General for both Tx watchdog and Tune ▼  
6
6
.6  
.7  
In DXpedition mode with WSJT-X, the hounds watchdog timers are fixed  
at 3 minutes. After calling the fox 6 times, our transmitters are  
automatically disabled if we haven’t had a reply. We can simply click  
enable Tx to continue calling the fox … but it’s a good idea, first, to take a  
moment to check that our Tx frequency remains clear during the even  
periods when we would be transmitting.  
We are more  
likely to be heard  
by the fox on a  
clear frequency.  
This is DXing 101.  
Select Auto Seq. Auto-sequencing works quite well  
“The auto sequencer is doing the  
with FT8, reduces operator stress and cuts down on  
newbie operating errors (e.g. not selecting the next  
message in time, not the correct one anyway). If  
Auto Seq gets it wrong, you can override the auto-  
selected message by quickly clicking the Tx message  
button for your choice of message. If you do this  
during the first few seconds of your transmission  
equivalent of double-clicking each  
response from your QSO partner ... A  
QSO will be ‘correctly’ sequenced by  
double-clicking each of your QSO  
partner's responses as they arrive. This  
is how you would normally use the  
application in modes without auto-  
sequencing like JT9 and JT65 although, of  
course, you can click through the next  
message manually as well: automation is  
an aid not a necessity.” [tnx Bill, G4WJS]  
(
during the synchronisation segment), the revised  
message will probably be sent as intended. If you  
arent quick enough, the message may be corrupted.  
Alternatively, there’s the 100% manual option ►  
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FT8 Operating Guide  
6
.8  
If you inadvertently select one of the Contest options under F2  
Settings  Advanced in WSJT-X you will be perplexed to  
discover weirdness in your generated messages and  
sequences▼  
Stop tinkering with random  
settings or you’ll be sent to  
the naughty step!  
5
Deselect (un-tick) Special operating activity to resume normality.  
5
JTDX does not support contests.  
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FT8 Operating Guide  
7
How to respond to a CQ, or call a specific station  
7
.1  
First set things up:  
Set up WSJT-X or JTDX to control the rig using CAT.  
Set the receive and transmit audio levels and the rig’s power level correctly.  
Find a clear slot  
on the waterfall  
and shift-click  
(
WSJT-X)  
right-click (JTDX)  
to set your  
transmit  
frequency there.  
Enable/select  
Auto Seq and  
Hold Tx Freq.  
Check the WSJT-  
X
F2 Settings  
General and  
select Double-  
click on call sets  
Tx enable ►  
Show DXCC entity  
and worked before  
status  
decoded  
highlights  
CQ  
messages that are  
new ones for you on the Band activity pane.  
Double-click on call sets Tx enable makes it dead easy to respond to a standard CQ message: when  
you double-click a decoded message, WSJT-X does several things for you:  
It puts the other station’s callsign and gridsquare (if they sent one)  
into the DX Call and DX Grid boxes on the main window, displaying  
the short path beam heading (if they sent a grid).  
Select Tx messages  
to Rx frequency  
window to see your  
outbound and  
inbound messages  
in contrasting  
background colours  
show this.  
It generates the standard messages you will send, with their callsign  
and your report to them inserted.  
It selects the appropriate transmit periods, even or odd, the opposite  
of whichever periods the DX station is using.  
It copies the decode you clicked to the bottom of the Rx frequency  
pane on the right.  
It selects message Tx 1.  
and finally …  
It sets Tx Enable so you will start transmitting when it’s your turn.  
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FT8 Operating Guide  
7
.2  
Before you double-click a decode to call someone, select a suitable transmit frequency. Shift-click  
(WSJT-X) or right-click (JTDX) on a clear space on the waterfall to put the red goalpost there.  
The CQing station doesn’t need to say up 3 or anything else. He will decode all stations in the  
audio spectrum. You can call him at 300Hz or 2300Hz and it won’t make any difference. They  
all display. You don’t have to (and don’t want to) move to his frequency. If there is more than  
one station calling him, they will hopefully be spread all over the audio spectrum, not causing  
QRM to the station trying to make a QSO or each other. If a bunch call on his frequency, they  
just QRM each other and the guy CQing will be working those who are split. Additionally, if he  
starts a QSO with someone close to your transmit frequency, your transmitter will be disabled  
so you don’t cause him QRM. If you are transmitting further away, you can keep calling him and  
he should pick you up as he works through the list of callers.” [Tnx Gary AG0N]  
Three strategies for picking your Tx frequency  
1
. The easy approach is to pick a clear frequency (i.e. a blank column on the waterfall) and hope  
it is also clear for those you want to contact. This strategy works well on a quiet band but is  
less effective when the band is chockablock. There may be no blank columns! A less-busy  
frequency may be your only option e.g. partially overlapping one or two other stations, or  
somewhere near the left or right sides of the waterfall (although the DX station’s filters may  
cut off more sharply than yours).  
2
3
. If the DX station doesn't appear to copy you at all for a few transmissions, move to a different  
transmit frequency. Likewise, if a QSO appears to stall, the DX station repeating the same  
message to you several times … eventually giving up on you to work someone else.  
. Avoid calling ‘simplex’ on the same frequency as a DX station, except as a last resort. Naïve  
FT8 users tend to call ‘simplex’, QRMing each other in much the same way as a pileup on the  
legacy modes. The rarer the DX, the worst this problem becomes. He will struggle to copy  
anyone reliably, unless by chance most stop calling and the frequency goes quiet.  
[
Tnx Jeff, WA1HCO]  
7
.3  
You can call anyone you like … but you’ll find it more productive  
to call stations you can actually copy, at the right moment.  
There is a silent DE in most  
messages. “S9A ZL2iFB RF80”  
means “S9A DE ZL2iFB RF80”.  
Stations you can actually copy’ are the ones sending the  
second callsigns in messages containing two callsigns e.g.  
S9A ZL2iFB RF80  
ZL2IFB S9A JJ30  
ZL2IFB S9A -23  
ZL2IFB S9A RR73  
TNX TIPS GARY  
These messages  
were all sent  
by ZL2iFB:  
These messages  
were all sent  
S9A ZL2iFB -21  
S9A ZL2iFB RR73  
TNX NEW 1 73  
by S9A:  
If you intend to call S9A, the best way is to browse through the lefthand Band Activity pane to find  
a standard message sent by S9A (i.e. one with some other callsign first, then S9A, ending with a  
locator, signal report or RR73 message) and double-click that. Your system will normally start  
calling him at the start of his next listening period. If he is in QSO with someone, your transmission  
may be sent at the same time as the station he is working … which may cause QRM unless you are  
transmitting on a clear frequency (hence the previous advice). If not, quickly click Halt Tx to stop  
transmitting and wait until the QSO is over before clicking Enable Tx to start calling.  
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FT8 Operating Guide  
7
.4  
If you cannot find a  
Please, only call stations you can copy! From the DX perspective,  
it is very frustrating to be called by people that are evidently not  
copying us. We waste our valuable time pointlessly responding to  
them when instead we could be working the deserving.  
Remember that DX stations are often in remote, low-noise  
locations, hence they hear pretty well. If you live in a town or city  
surrounded by nasty switchmode PSUs and other hams, you will  
struggle to hear the DX … so wait patiently until you decode at  
least one message from the DX, and spend the time wisely. Try  
turning your beam, improving your station, locating and replacing  
those nasty switchmodes with nice linear supplies, or persuading  
your significant others that rural life is wonderful. The grass really  
is greener out in the countryside.  
message sent by the DX  
station in your Band  
Activity lefthand pane,  
that’s probably because  
you are not receiving him  
well enough to decode his  
6
messages . There is little  
to no point calling him as  
you will probably not copy  
his response, even if he  
copies and responds to  
you. Your transmission is  
wasted.  
7
.5  
The software prepares (generates) the standard messages Tx 1 through Tx 5 when you:  
Double-click a decoded message. The callsign of whoever sent the decoded message appears  
in the DX Call box and is inserted into the standard messages Tx 1 to Tx 5, along with your signal  
report for him (i.e. the signal-to-noise ratio in decibels as measured on the most recent message  
received from that station) in messages Tx 2 and Tx 3.  
Type a callsign into the DX Call box and then click the GenMsgs button.  
7
.6  
This is how JTDX looks while it is decoding  
This shows JTDX while it is  
the latest audio capture from the radio ▼  
transmitting message Tx 2 ▼  
The grey radio button next to Tx 2 shows  
which message will be sent next …  
… and the Tx 2 button turns green and enable  
Tx goes red while it is being transmitted.  
6
Browsing back through the Band Activity pane is a pain because it resets to the bottom as each new batch of decodes is  
displayed. We can stop it updating by de-selecting the Monitor button or turning off the receiver. One day maybe we’ll  
persuade the developers to let us freeze the pane by mousing into it, thawing it when we click a decode or mouse away.  
Copyright © 2021 ZL2iFB  
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FT8 Operating Guide  
7
.7  
.8  
.9  
If the other station copies you calling him and responds to you, you’ll see his response (usually  
your-callsign his-callsign his-report-to-you) appear at the bottom of the Rx Frequency pane, and  
Auto Seq will automatically select your next message to send (Tx 3 - with an R before the report  
confirming that you have Received his  
If you are not prompted to log the QSO, check the  
report to you). He’ll respond with an RRR or  
configuration settings. The software may be  
RR73 message, and you will send your 73  
logging QSOs automatically and silently for you  
message. The box will pop up prompting  
as they are completed … or it may not be logging  
you to log the QSO and Enable Tx will be  
QSOs at all. Oh oh.  
unset, and that’s it, you’re done!  
7
If double-clicking a CQ message doesn’t do anything, that usually means the DX station is (perhaps  
inadvertently) using a free-text message rather than one of the standard predefined message  
types. The auto-responder doesn’t recognise it as a CQ message, so doesn’t know how to respond.  
Even if a free-text message happens to contain the string “CQ” and looks like a CQ (such as “CQ  
ZL2 M0NKR”), it still isn’t interpreted as a CQ message. The solution is either to double-click a  
different decoded line from the same DX station in the hope that it is a standard message, or  
manually type his callsign into the DX Call box, click Generate Std Msgs, select your Tx 1 or Tx 2  
7
message , and click Enable Tx to start calling him. This is a reminder not to get too fancy with your  
CQ calls.  
7
7
Aside from shift-clicking the  
waterfall, another way to shift your  
Tx frequency is to nudge it 60 Hz LF  
using shift-F11, or 60 Hz HF using  
If you change your mind after QSYing, these fixed-step  
nudges are readily reversed, whereas there is no easy way  
to revert automatically to your previous Tx frequency  
after shift-clicking or right clicking.  
shift-F12.  
.10 Keep an eye on the decodes while you are calling someone. DX  
stations sometimes disappear, perhaps temporarily or  
permanently going QRT, dropping in QSB or QSYing. If you  
notice other stations calling the same DX you are calling, stop  
transmitting for a cycle or two to figure out what’s going on:  
maybe the DX has swapped between even and odd slots to  
evade a stalker. Make sure you are calling him when he is  
listening! Maybe he has moved a few kHz away to use  
DXpedition mode (fox-n-hounds).  
Although there’s a lot going  
on in the minute or so it  
takes for an FT8 QSO, most  
of it is automated ... and,  
trust me, it gradually  
becomes less stressful as  
you log more QSOs and gain  
confidence.  
8
7
.11 In order to set your primary Rx and/or Tx audio frequencies, pick from these ten options:  
1
2
3
. Click somewhere on the waterfall to put your Rx there9.  
. In WSJT-X shift-click or in JTDX right click on the waterfall, to put your Tx there.  
. In WSJT-X right-click on the waterfall for the option to put both the Tx and Rx there.  
7
If you forget to select Tx 1 or Tx 2, WSJT-X will send your CQ message Tx 6 instead. Probably not what you wanted!  
I say ‘primary because the software attempts to decode all the signals it finds, wherever they happen to be across the entire  
8
audio bandwidth as seen on the waterfall. The green Rx frequency marker allegedly indicates the region that is decoded first  
and deepest, although in practice on the HF bands I don’t notice any difference. It is safe to ignore the green marker.  
9
I find no reason to do this. See previous note. The software supposedly moves the Rx marker to the audio frequency of  
whoever we are working but on my system it often doesn’t … and yet I make QSOs just fine. Ignore the green marker!  
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FT8 Operating Guide  
4
. In WSJT-X, uncheck Hold Tx freq to have your Tx jump to  
another station’s frequency as you double-click their CQ  
message (a bad idea, especially when calling a DX station  
busy with other callers).  
In JTDX, Hold Tx freq is  
always active and cannot  
be disabled. Cool.  
5
6
7
. Enter your choice of audio frequency directly into the Tx or  
Rx box.  
. Click the little up or down arrow buttons next to the Hz label in the Tx or Rx frequency box to  
shimmy up or down 1 Hz per click. Click and hold to send a staccato series of clicks.  
. If necessary, click to put Windows’ focus on the main WSJT-X screen or the waterfall, then  
press F11 or F12 to slide your Rx left or right respectively. Hold the Ctrl key to increase the  
rate of slide from 1 Hz to 60 Hz per click.  
1
0
8
9
. Click to focus then hold shift and press F11 or F12 to slide your Tx left or right respectively .  
. Double-click a CQ message from someone specifying an auto-QSY VFO frequency (not  
recommended on HF).  
1
0. Stay put while you read the online user guide or press F3 and read about the shortcut keys, or  
F5 to read about the special mouse commands (commands for special mice!).  
7
.12 Two distinct things, working together, determine your transmit and receive RF frequencies:  
1
. Your transceiver’s VFO frequencies on transmit and receive. Normally these are the same  
‘simplex’) but they may be different (‘split’ or ‘crossband’) and  
(
2
. The audio frequencies generated by the selected PC sound card as directed by WSJT-X or JTDX.  
When you select a band in WSJT-X or JTDX, it  
commands your CAT-connected rig11 to set  
the VFO to the specified frequency such as  
1
4074 kHz for 20m, and optionally sets the  
mode according to the F2 Settings  Radio  
tab . If your radio offers a data mode, try  
that. If not, use USB (on all bands) but be sure  
to disable any speech processing.  
7
.13 The red goalpost marker above the waterfall  
shows the audio frequencies of the tones that would be generated if you transmitted on the  
chosen VFO frequency  but … if you have sensibly selected one of the Split Operation options  
under F2 Settings Radio, and positioned the red goalpost marker towards the left or right sides  
of the waterfall, things may get interesting:  
The Rig setting can use the rig’s built-in split function to move the transmit VFO (usually VFO B)  
relative to the receive VFO (usually VFO A) if it needs to compensate for a difference in the  
audio frequencies generated (see below).  
1
0
1
Be lucky: on my system, the shift F11/F12 thing stops working after WSJT-X has been running for a while. Just my luck.  
If your rig is not CAT controlled, you’ll have to change frequencies the old-skool way using its knobs and buttons.  
1
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FT8 Operating Guide  
The Fake It setting can QSY the main VFO on transmit if it needs to compensate for a difference  
in the audio frequencies generated (see below), and QSY back to the original VFO frequency on  
1
2
receive .  
The ‘difference in audio frequencies generated’ comes about because very low or very high audio  
frequences are likely to be attenuated by your transmitter’s audio filtering . Most amateur  
sideband transmitters have a restricted audio range of approximately 200 Hz to 3 kHz, sufficient  
for intelligible speech, similar to the telephone, but their filters attenuate or roll-off audio  
frequencies at the lower and upper edges of the range.  
1
3
Using Split Operation, WSJT-X and JTDX can move the transmit VFO HF or LF in 500 Hz steps while  
generating audio at the same number of 500 Hz steps in the opposite direction. This is how the  
Split Operation function works with Fake It ▼  
Example 1 shows someone with the red goalpost sitting just above 2200 Hz on the waterfall. At  
that audio frequency, the rig’s sideband filtering may start to roll-off the level, reducing his output  
signal strength. Therefore, the software shifts his transmit VFO 500 Hz HF and simultaneously  
drops the generated audio 500 Hz LF to just above 1700 Hz, right in the sweet spot between 1500  
to 2000 Hz where the rig’s transmit audio passband is liely to be flat. The net result of those two  
shifts is that his output signal emerges as if by magic just above 2200 Hz where the red goalpost  
sits, but at full strength.  
12  
Fake it works even on single-VFO radios provide they are CAT controlled. If you are using a boat-anchor or basic rig without  
CAT, it’s a good idea to keep the red Tx marker away from the left and right ends of the waterfall. Keep to the safe middle  
ground.  
13  
Naïve ops who notice low rig ALC levels [when they are transmitting from either end of the waterfall] sometimes increase  
the PC audio output to the point that the transmitter’s microphone input is overloaded, causing them to transmit audio  
harmonics that we see as ghostly barcodes. ‘Rig’ or ‘Fake it’ reduces this possibility.  
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FT8 Operating Guide  
Example 2 shows what happens when the red goalpost  
was  
Recently  
I
noticed that  
I
is set below 1500 Hz on the waterfall. The VFO and  
audio both shift by 500 Hz in opposite directions to keep  
the audio frequency in  
sometimes being spotted on FT8,  
apparently using a different TX audio  
offset than I had set. Eventually I  
twigged that the rig was not operating  
in split mode: the split command from  
JTDX was being rejected by the radio  
due to a mode conflict between the  
K3s VFOs (or something!). Clicking  
The sweet spot is  
deliberately restricted to  
the upper part of the rig’s  
flat audio passband such  
that if the audio stages are  
accidentally over-driven,  
any audio harmonics  
should be attenuated by  
the filtering, producing  
cleaner signals.  
the sweet spot while  
again the output signal  
ends up on the  
intended frequency at  
full strength.  
the rigs front panel AB button twice  
cleared it up, and now I keep an eye on  
the LCD display for the SPLT indicator,  
especially after changing bands.  
So, don’t panic if you  
see your rig’s VFO move  
when you go to  
transmit: it’s all under  
1
4
control .  
14  
Well, usually it is under control. There are occasional reports of the rig ‘walking’ a further 500Hz LF or HF on each over –  
presumably something screwy in the CAT comms. Cue the IT help desk: “Have-you-turned-it-off-and-on-again?”.  
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FT8 Operating Guide  
8
How to call CQ  
8
.1  
Hopefully by now you have your system working on  
both receive and transmit. Get ready to call CQ by:  
Setting the Hold Tx Freq, Auto Seq and Call 1st  
options on the WSJT-X main window, or AutoTX,  
AutoSeq and Tx/RX Split in JTDX.  
Clicking the Tx 6 message box or button, or hitting  
F4, to select your CQ message if not already  
1
5
selected: look for the Next selector blob ►  
8
.2  
Before you start calling CQ, study the waterfall for at  
least a couple of cycles. Look for two things: (1) a suitable space in which to transmit, ideally a  
clear column; and (2) any strong/local stations already transmitting. If you’re lucky, there will be  
no angry red blobs on the waterfall from signals strong enough to trigger your receiver AGC, and  
none radiating wideband noise or audio harmonics to interfere with your reception and decoding  
of weak DX signals. If you are having trouble from one station, it helps to synchronise your  
transmissions with him so that both of you transmit and listen at the same time  so choose the  
same even or odd cycles. That’s not always possible, for instance if there are strong or poor quality  
signals from both even and odd-cycle transmitters. So, do the best you can. Fiddle with your radio  
settings if that helps e.g. reducing RF gain or adding attenuation; turning your beam away from  
the QRM; using high/low-cut filters or a notch; turning off the AGC. Perhaps take a break or try a  
different band. Above all, keep your cool. This is all part of the challenge  and the ‘fun’ – of DXing.  
Rise above it. Be like DX boss.  
8
.3  
Now, to CQ, simply click the Enable Tx  
button to start calling CQ. That’s all  
there is to it! If everything goes to  
plan, within 15 seconds or so the rig  
The software can only ‘Generate Std Msgsif you  
double-click a decoded message, or enter a callsign into  
the DX Call box first: otherwise the only message it can  
generate is Tx 6, the CQ message with your own  
callsign, assuming you have configured that under F2  
Settings General tab.  
will go into transmit and you’ll see the  
CQ message at the bottom left of the  
being  
main  
WSJT-X  
window  
transmitted.  
15  
Being able to pre-select the next message to be sent can be handy during the course of a QSO, for instance to send a specific  
free-text message at the end of the current QSO, even while your RRR or RR73 message is being sent. However, neither WSJT-  
X nor JTDX handle this very well. In particular, our chosen or custom-written free text messages are often reset to the default  
boring 73 message, summarily erasing our planned message without warning. It’s a bit of a juggling act, sometimes, manually  
wrestling with the autosequencing logic. It can help to turn off the autosequencer temporarily  just remember to turn it back  
on afterwards!  
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FT8 Operating Guide  
8
.4  
When someone responds to your CQ, Auto Seq takes you though the conventional QSO sequence,  
automatically. It sets up the messages with both callsigns, and sends them their report using  
message Tx 2, or Tx 3 if they have already sent you your report. Next one of you sends RRR  
meaning ‘all received’ or RR73 meaning ‘all received, best wishes and thanks for the QSO’. Either  
of you may send Tx 5 containing the standard 73 message or something bespoke  just 13  
characters, though, similar to SMS/TXT messages. Provided the message you transmit contains  
the string “73” somewhere, WSJT-X interprets that as the final message of the QSO and pops up  
the logging panel for you, assuming you are using the F2 Settings Reporting option “Prompt me  
to log QSO” ▼  
1
6
At the same time, Enable Tx is automatically unset , giving you a moment to savour the QSO ... or  
click Enable Tx to start the sequence again with a fresh CQ.  
The requirement to click Enable Tx to re-start the QSO sequence is not an accidental  
oversight in the software but a deliberate, conscious choice by the team behind FT8  
and WSJT-X. By design, WSJT-X will not robotically fill your logbook for you.  
8
8
.5  
.6  
If someone else has called you already (a tail-ender), you can double-click their decode to respond  
without sending another CQ first, but you must wait until the previous QSO is complete and your  
final message is sent: if you double-click too soon while your 73 message is still being transmitted,  
the 73 message will be aborted and you’ll start calling the tail-ender instead, perhaps transmitting  
a corrupted and undecodable message. That’s not cool.  
st  
st  
Call 1 automatically responds to the first decoded With both Enable Tx and Call 1 selected,  
caller  literally, the caller whose message pops out WSJT-X will automatically respond to the  
of the decoder first, anyone from anywhere who first decoded station who calls you after  
responds to your call: if you want to choose which you have logged the previous QSO, even  
st  
callers to QSO, turn off Call 1 and double-click the if you don’t send a CQ. It doesn’t queue  
decodes from the callers you want to work, ignoring up callers though, so they have to call you  
the riff-raff. You have more autosequencing options at the end of your QSOs. JTDX does  
with JTDX, so read the notes and try them out.  
appear to queue premature tail-enders.  
8
.7  
If the auto-responder responds to someone but you  
would rather have responded to or called someone else, within the first second or so of your  
transmission you can hit F4 to clear the current respondee, then double-click a decode from the  
wanted station. The F4 step is necessary, unfortunately: it would be easier if we could just double-  
st  
click the decode to respond to that one, even with Call 1 selected, but without F4 the double-  
click is ignored.  
1
6
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st  
selected. Personally, I think that’s a bug in WSJT-X. I find it inconsistent and disconcerting to discover that the Call 1 option  
affects the end of QSO behavior. Maybe it’s just me.  
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FT8 Operating Guide  
8
.8  
Customize your CQ calls by editing the Tx 6 message in the  
format “CQ XXXX ZL2IFB RF80” where XXXX consists of UP TO  
FOUR LETTERS e.g.:  
Be careful with this: you only  
get to play with those 4 letters.  
If you enter 5 letters or include  
numbers or punctuation, your  
CQ call becomes a free-text  
message with the 13-character  
maximum: on receipt it is not  
automatically interpreted by  
WSJT-X as a CQ message, hence  
nothing happens if a recipient  
double-clicks it. So don’t do it!  
A continental indicator such as AF, AS, NA, OC or SA, or  
17  
two such as AFEU or NASA (!), or DX , UK, USA, ASIA, AP  
or APAC (Asia/Pacific), or your antenna direction such as  
EAST or NNW, or EULP or JALP, or LEFT (as in left coast) …  
An explicit exclusion such as NOEU, NOJA or NONA  
One or two state indicators such as VT, RI, NDSD …  
One or two letter-only prefixes such as PJ, JA, VKZL, VP …  
SPLT, SPRD or BLOB meaning “Please call me split not  
simplex! All I see is a nasty red blob on my Tx frequency!”  
Q codes etc. may be handy if  
someone  
you  
notice  
apparently responding on  
your Tx frequency to your  
CQ but you cannot decode  
their messages.  
A Q-code such as QRZ, QRO, QRP, QRM or QSY, or an  
abbreviation such as AGN or WEAK  
IOTA, SOTA, TEST, IGC etc. indicating that you are operating  
from an island or summit, or in a contest or  
challenge, and/or would prefer to contact someone  
who is  
Custom messages tend to evaporate  
when the software regenerates the  
standard messages e.g. when you  
log a QSO. Don’t blame me!  
An abbreviated club name such as CDXC, ARRL, JARL,  
RSGB or NCDX maybe  
8
.9  
If recipients double-click any valid CQ message, their  
systems will generally respond regardless of their locations. Rude hams evidently don’t read or  
don’t care about targeted CQs, calling even if they are nowhere near the target. It is up to the  
CQer, then, to decide whether to make a QSO with them or wait patiently in hope of a call from  
1
8
someone in the bullseye.  
As someone who has a very limited location for  
antennas (they are all in the loft!) and for DX (I live in a  
valley), I’ve found FT8 a brilliant way of achieving QSOs  
that would be quite impossible with most other modes.”  
Bryan G4KRO  
17  
DX means whatever the sender thinks it means. There is no formal or universal definition. Oh HF, it may mean another  
country, another continent, the far side of the world, a top N most wanted DXCC, anything vaguely exotic, or something else  
entirely. For those using microwatts, a mile or two may qualify as DX! For EMErs it could mean little green men from Mars.  
18  
JTDX gives us the option to auto-respond ONLY to targeted callers … but even JTDX doesn’t understand “CQ DX”!  
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FT8 Operating Guide  
8
.10 It’s entirely up to you whether to transmit, what to transmit, when  
and where … but some hams get their knickers in a twist if you do  
something unexpected or unconventional. It is conventional but  
not mandatory to end HF QSOs with the exchange of 73 messages.  
Some FT8 users feel  
snubbed if they don’t  
receive a 73, stubbornly  
refusing to log the QSO  
on principle. It’s their  
choice. It’s only a hobby.  
If you do not receive a 73 from the other  
The golden rule is  
party, tough: perhaps it got lost en route,  
to log the QSO  
swallowed up by the ionosphere. Get over  
whenever we  
it! If they stop sending or start CQing, it’s  
send an R  
message.  
fair to assume they believe the QSO is complete so you are probably in  
their log.  
8
.11 The Halt Tx button is immediate  it aborts the current  
transmission in progress (if any) and de-selects the  
Enable Tx button so it won’t transmit at the start of the  
next sequence. De-selecting the Enable Tx button,  
however, allows the current transmission (if any) to  
continue normally to completion. You don’t need to click  
it at the very end of the transmission or wait until the  
receive period click it whenever you don’t want to  
transmit in the next transmit period.  
When you want to take a break, de-  
select Enable Tx at any time during  
or following your final transmission.  
If you can, keep an eye on the  
screen for a while longer in case of  
a delayed response when your call  
reaches the head of the fox’s  
queue. He might bite anyway.  
[Although] WSJT-X requests audio sample streams at 48000 Hz 16-bit depth, that does not  
mean that other sample rates and formats are not supported. The operating system and audio  
subsystem will convert to or from the nearest available hardware sample rate. While sample  
rate or format conversions are undesirable, they are not necessarily problematic, e.g. some  
conversions are trivial computationally such as reducing bit depth from say, 24-bit to 16-bit,  
which only requires low order bits to be discarded, likewise down/up converting the rate by an  
integral factor is also trivial such as converting a 96000 Hz or 192000 Hz input stream to 48000  
Hz. On the other hand, converting a 44100 Hz input stream to 48000 Hz involves complex re-  
sampling which is expensive and inaccurate and could even cause audio dropouts on a slow PC.  
WSJT-X currently down samples to 12000 Hz as a first processing step on Rx, this is sufficient to  
support an audio bandwidth of up to 6000 Hz which is all that is needed for the modes supported  
by WSJT-X. We request a 48000 Hz stream as this is commonly available all almost all audio  
codecs of suitable quality for WSJT-X use. Using higher sample rates adds no benefit, it simply  
adds unnecessary computation for no gain in performance whatsoever. The same applies to bit  
depths greater than 16-bit.”  
Bill G4WJS  
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9
Logging digimode QSOs  
9
.1  
At the end of a QSO, JTDX and WSJT-X normally prompt you to log the QSO. In more detail:  
‘At the end of a QSO’ means when you receive a Tx5 message, specifically a Tx5 message  
containing the text “73”.  
o Consequently, if you edit the generated Tx5 message, it is best to leave the “73” in there  
so that the other party is prompted to log the QSO, or logs it automatically.  
o If the Tx5 message is not sent to you, not received by you or does not contain the magic  
<
73, you will have to log the QSO manually by clicking the Log QSO button or typing  
Alt+Q>.  
1
9
I said normally because if so configured, JTDX can automatically log completed QSOs:  
o Tap F2 to open the Settings.  
o Click to open the Reporting tab.  
o In the Logging section of the form (top left), select (tick) Enable automatic logging of  
QSO which de-selects Prompt me to log QSO if that was set (it is the default).  
o Click OK at the foot of the form to save the settings and continue using JTDX.  
9
.2  
When a QSO is logged, two records are written to disk:  
A text record is appended to a .log file, of the form:  
021-09-06,03:50:33,2021-09-06,03:51:14,RV3ID,KO77,14.076359,FT8,-05,-19,,,  
And an ADIF record is appended to an .adi or .ADI file, of the form:  
2
<
<
<
<
call:5>RV3ID <gridsquare:4>KO77 <mode:3>FT8 <rst_sent:3>-05 <rst_rcvd:3>-19  
qso_date:8>20210906 <time_on:6>035033 <qso_date_off:8>20210906  
time_off:6>035114 <band:3>20m <freq:9>14.076359 <station_callsign:6>ZL2IFB  
my_gridsquare:4>RF80 <eor>  
19  
Because the WSJT-X team is determined to prevent their software being used robotically to make and log QSOs  
automatically, I understand WSJT-X does not natively offer automatic QSO logging. The JTDX team is less adamant, hence JTDX  
can automatically log completed QSOs, which means less chance of completed QSOs remaining unlogged simply because we  
neglected to click the log QSO button.  
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FT8 Operating Guide  
The text and ADIF log files are stored in your  
AppData\Local folder. The easiest way to get to that  
folder is to use File Open log directory ▶  
WSJT-X and JTDX use virtually the same log file name  
(
wsjtx_log.ADI for JTDSX and wsjtx_log.adi for WSJT-  
X) in their own directories (folders) within the  
AppData\Local folder a windows folder that is  
normally hidden by Windows Explorer to stop inept  
users messing up their systems.  
On your system, your WSJT-X ADIF log file is probably  
at %localappdata%\WSJT-X\wsjtx_log.adi You can copy and paste that string into the  
Windows Explorer directory field. The %localappdata% bit is a ‘system environment variable’  
that gets expanded by Windows, taking you to wherever the AppData\Local folder is located on  
your see  
With a few optional exceptions (“Fox” operation in FT8 DXpedition mode, and  
contest operation), user action is also required to verify QSO details and submit  
them for logging. In any event, by design WSJT-X requires that every QSO must be  
initiated by a human operator. We do not like the idea of fully robotic operation  
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FT8 Operating Guide  
10 Hinson tips: miscellaneous FT8 operating tips  
This chapter is an assortment of answers to Frequently Asked Questions, blended with a bunch of helpful  
hints contributed by experienced FT8 HF DXers.  
1
0.1 Generally speaking, it’s best to turn off the rig’s noise blanker,  
narrow filtering and fancy DSP Noise Reduction for digimodes:  
let the sound card and computer software do its thing,  
extracting signals from noises ... but  you may like to  
experiment with the settings (e.g. IF shift, high- or low-cut or  
your notch filter may reduce overloading and AGC depression  
caused by strong signals such as W1AW news broadcasts or  
over-the-horizon radar). Some users report good results with  
the rig’s DSP noise filtering (e.g. +5 dB with NR on an Icom IC-  
Don't ignore that narrow  
CW filter in your radio! A CW  
filter will pass narrow digital  
modes just fine. While it is  
generally a good idea to listen  
wide so you can see all the  
traffic in the band segment,  
when you are trying to dig  
that weak one out through  
the cacophony it can help to  
put your narrow filter on him.  
Try it!” (Tnx Jim, NU0C).  
7
200 according to Hans DK2XV, in the presence of switchmode  
PSU QRM). There’s no harm in finding out for yourself.  
Compare the results with and without DSP  see what works  
best for you, producing the clearest waterfall, the most  
decodes or the highest average reception reports.  
Here's an example of the value of narrow filtering, captured on my WSJT-X waterfall ▼  
The big red blobs on the lower left of this waterfall are a couple of local ZLs with massive FT8  
signals on a wide-open 20m at peak time (one of them over-driving his rig’s audio input, causing  
the ghostly barcodes around 1870 Hz). The red blobs at about 1850 then 1900 Hz towards the top  
of the waterfall were from a Kazakhstan station calling me via the long path. I quickly raised the  
lower edge of the K3’s filter to cut off the locals, preventing their signals from depressing the AGC,  
causing the black/dark speckly area up to 1400 Hz with no big red blobs. At the same time, the  
signals in the passband, including the UN7, became markedly stronger and we completed our LP  
DX QSO.  
This filtering trick works for any signal that you can locate on the waterfall. The waterfall itself  
shows the effect of narrowing the rig’s filters and shifting the filter centre frequency. If your rig’s  
filtering is not so flexible, using the RIT to shift strong signals out of the passband may help.  
1
0.2 If you change the free-text message in Tx 5 but want to revert to the default message, simply  
double-click the Tx 5 button. The other Tx messages can be regenerated on demand by clicking  
the “Generate msgs” button (“GenMsgs” in JTDX) provided the DX station’s call is still in the DX  
Call box.  
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1
0.3 Messages are appended to the left and right hand windows in the sequence they emerge from the  
logic. They are not - and unfortunately cannot - be sorted according to frequency, callsign, country,  
strength, distance, worked before status, needed status or anything else and sometimes appear  
distinctly disordered:  
Messages emerge sequentially from each round of decoding, first the ‘easily’ decoded signals,  
then the ones that took deeper analysis. Magic is happening here in the decoder algorithm –  
don’t knock it!  
Your transmit message might be sent to the encoder and displayed on the screen with its  
current timestamp before a deep decode from the previous period is, belatedly, appended with  
its earlier timestamp.  
When you double-click a message, it is repeated at the bottom of the righthand window.  
1
0.4 Especially when the band is humming and the DX is busy, spread  
out! Any decoded message containing your callsign will be  
displayed on your Rx frequency pane, wherever it is being  
transmitted on the waterfall, so there is no need to work  
simplex. Unlike the legacy modes, calling or working simplex is  
generally not a good idea on FT8, especially with any popular  
station since others will generally be doing the same, QRMing  
each other. Hasan N0AN put it very well:  
Calling someone simplex  
while they are in QSO with  
someone else is rude and  
inconsiderate. If you do it to  
me, I may deliberately ignore  
you. If you were in the  
shack, I’d give you a slap.  
Don't call me on my Tx freq, as it is full of callers  
Unlike conventional legacy modes, split operation is  
Don’t forget that each party to an FT8  
preferred by most FT8 DXers. The idea that split  
QSO transmits in sequence. Even and  
operation on FT8 “ties up two frequencies for one  
QSO” and is therefore an inefficient use of spectrum is  
a naïve misunderstanding. ►  
odd periods are orthogonal and  
should be considered separately.  
Within each period, each party is  
Rather than zero-beat to using one thin slice of spectrum, just  
call someone on their 50 Hz wide. After they end their  
working frequency, take a transmission, the frequency is  
moment to shift-click your released for anyone else to use during  
Tx signal (the red goalpost the next 15 second period. See  
Split operating is not a  
hard-and-fast  
rule.  
It’s not the law, just a  
tip that experienced  
FT8 DXers find works  
better in practice than  
simplex. Try it!  
above  
the  
waterfall) Appendix E for a more elaborate  
elsewhere on the waterfall, explanation.  
somewhere quiet.  
What does make inefficient use of our shared spectrum is when several people all pile up on the  
same frequency, QRMing each other, leading to repeats, delays, abandoned QSOs and intense  
frustration. Another inefficient practice is calling continuously or out-of-turn, especially calling  
right on top of a QSO in progress  again something that is made worse by multiple people  
attempting to use the same working frequency simultaneously. It’s not so much that zero-beat  
simplex operating is inherently bad and patently it does work, rather that split works even better  
on FT8.  
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1
0.5 Higher transmit frequencies towards the right of the  
Spare  
digihams. Stay within the FT8 sub-  
1) Harmonics caused by overdriving something in the band: weak signal DXers using  
a
thought for other  
waterfall are slightly advantageous for two reasons:  
(
audio chain are more likely to be blocked by your rig’s Olivia, JT65, JT9 and other  
transmit filters [don’t rely on this though! Keep your digimodes, mostly above 2500 Hz  
audio level down!]; and  
2) On a busy band, decodes in the band activity pane  
scroll past quickly in frequency order, so anyone CQing  
or so on the waterfall, will not  
appreciate you stomping all over  
them. You may not even see their  
signals on the waterfall: that’s why  
it’s called weak-signal DXing!  
(
towards the left of the waterfall is more likely to scroll off  
2
0
the top of the pane . However, don’t go too far to the  
right of the waterfall ►  
If the station you are calling is  
very weak, others who cannot  
hear him may inadvertently  
cause QRM by choosing his  
frequency to CQ. You might try  
sending a message or two  
simplex to let them know the  
frequency is in use. [Tnx tip Olaf  
DK2LO]  
Having said that, if someone you are calling seems to be  
ignoring you, it may help to move your Tx frequency closer  
2
1
to theirs , perhaps even simplex (not a good idea if they are  
DX). It is possible they are not receiving FT8 signals across  
the full sub-band shown on your waterfall, for example they  
may be using filters or may have their VFO offset. Maybe  
your chosen Tx frequency is busy with local QRM at their  
end.  
1
0.6 Especially when the band is busy, monitor for a couple of minutes before selecting your Tx  
frequency. Look for a continuous blank column on the waterfall, ideally, and shift-click (WSJT-X)  
or right-click (JTDX) to move the red goalpost there. Here’s part of the waterfall around 18100kHz,  
beaming at NA  Not bad for low power DXing on a seemingly deserted band! If I was planning  
to transmit in this range, I’d probably choose 1140, 1490 or 1650 Hz.  
2
0
It helps to stretch the WSJT-X window towards the full screen height: I can see about 40 decode lines that way. In JTDX,  
there’s room for about 45 decodes AND I can still see the waterfall showing about 6 periods right across the top of the screen.  
If for some reason you are not using CAT control of the radio hence the “Rig” and “Fake it” split options are unavailable,  
21  
remember to keep the red goalposts in the central area of the waterfall.  
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1
1
0.7 You may need to shift your Tx every few minutes on a busy band if other stations encroach on you  
such that the stations you are trying to work cannot copy you. Keep an eye on the waterfall and  
decodes.  
0.8 If you CQ, transmit in the same period as  
I gather on 6m and other UHF bands (!), there are  
the strongest signal/s on your waterfall to  
minimize mutual interference. Transmit  
when they transmit, receive when they  
receive. Dance the DX dance in-step.  
conventions on which slots to use when beaming  
East or West … but what do I know? I’m an HF  
DXer. On HF, we cope. We muddle through.  
1
1
0.9 Keep an eye on what’s going on. It’s tempting to set the Auto  
As with regular DXing, the key is  
to listen more than you  
transmit. It’s nature. Two ears,  
one mouth, remember.  
st  
Seq and Call 1 autoresponder options, then start CQing or  
calling someone and wander off ... but the sequencing  
function is easily confused by custom messages, or by  
messages received sequence out of.  
0.10 If you are CQing, making a run of QSOs or  
If your transmissions are being reported on  
calling and working several people, take a  
PSKreporter by stations wherever in the world  
break every so often to check that your Tx  
you seek to work, your chosen Tx frequency is  
presumably reasonably clear there.  
frequency and period remains clear. In WSJT-  
X, the easy option is not to re-Enable Tx  
overlapping signals, but  
weak signals are more likely  
to decode reliably on a  
reasonably clear frequency.  
immediately after you log a completed QSO -  
skip a Tx period. The lazy option is to wait for the watchdog  
timer to kick in. By taking a break, you may see other stations  
transmitting on ‘your’ frequency and period, or encroaching on  
Another technique I've found useful is, while transmitting, press Halt Tx, wait a couple of  
seconds then press Enable Tx and look at the waterfall on your Tx frequency. Frequently if  
your’ frequency remains open, others will be able to decode your transmission in spite of  
user-induced QSB.” [Tnx Bill AE6JV]  
it ... so shift-click yourself somewhere else on the waterfall. If you don’t take a break, you might  
think ‘your’ Tx frequency is clear whereas in fact someone else is sharing ‘your’ slot.  
1
1
0.11 The assorted screenshots in this guide are from my PC with my radio and my preferences. Yours  
may vary … so if you are going to make configuration changes, you might like to make a note of  
the changes as you make them so you can restore your original settings if the changes don’t work  
out.  
0.12 If, when you start transmitting, you hear what  
appears to be a single, plaintive, wavering tone in  
the headphones (similar to Tune), check on the  
lower status bar  that you are not in, say, JT9  
or WSPR mode. Narrow goalposts  above the  
waterfall are another clue. WSJT-X and JTDX  
both support several modes. Try ‘em!  
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1
0.13 If for some reason you neglect to log a QSO and forget the  
details (e.g. if someone emails you about a QSO with a  
missing confirmation and they aren’t in your log), the QSO  
info is probably stored in your ALL.TXT text file. Messages  
you have received and decoded, plus your transmitted  
messages, are saved sequentuially to ALL.TXT by default.  
It’s a plain text file. If you are very active on FT8 with WSJT-  
When I play with settings, I grab  
my phone and grab a quick  
screen shot of the setup screen  
so I know I can get it back without  
hassle.” [Tnx tip Gary AG0N]  
X, the file grows quite large: rather than simply deleting it, it’s a better idea to archive it  
occasionally in case you ever need to search for missing QSO info. JTDX makes this easier by  
opening a fresh ALL.TXT file each month e.g. in August 2018, as if by magic my ALL.TXT  
became C:\Users\Gary\AppData\Local\JTDX\201808_ALL.TXT  
1
0.14 Don’t worry too much about your Rx frequency: you can safely ignore the dead green goalpost  
above the waterfall, leaving WSJT-X to move it around for you. The software is decoding the entire  
waterfall, all at once, right? Well, yes and no: apparently it focuses on the area under the dead  
green goalpost, decoding first and more deeply there. So you might want to set the Rx frequency  
manually if you are monitoring some juicy but weak DX, waiting for him to complete QSOs so you  
know when to call. Also, on a busy band, the band activity screen scrolls too fast to ‘read the mail’,  
whereas, with fewer messages, the Rx Frequency pane scrolls at a far more sedate pace.  
1
1
0.15 Use the rig’s AGC or take care to adjust the RF gain control and attenuator whenever there are  
strong signals on the waterfall. Overload in the receiver and/or sound card can mess with any  
digital signal processing in your rig and on the soundcard including, WSJT-X’s decoding and  
waterfall display. AGC is the easy option, preferably on a slow setting since the software copes  
admirably with fading FT8 signals . Consider using your rig’s filters too.  
0.16 Please don’t continuously call someone who is calling or  
The software should automatically  
working someone else, even if you are calling them off-  
2
2
stop you calling someone simplex if  
they respond to someone else, but  
you should be keeping an eye on  
things and simplex operating is  
not recommended anyway.  
frequency . Be nice: wait your turn! It’s polite to wait  
until the DX sends RRR, RR73, 73 or CQ before calling  
them. If you call continuously, or try to barge-in on a QSO  
in progress (especially simplex), you will simply waste  
watts, create QRM, cause delay, and you may even be  
blacklisted by the DX.  
1
0.17 Use the waiting time wisely. Look at who else is QRV and where they are on the waterfall. Maybe  
shift-click (WSJT-X) or right click (JTDX) your Tx to a different, clear frequency. If you simply  
continue calling, you may be missing out on even more exotic DX stations who are transmitting at  
the same time as you!  
22  
JTDX is polite enough to stop us calling someone if they respond to someone else, regardless of our Tx frequency. WSJT-X  
only stops us calling if we are transmitting on or close to the station we are calling. I consider that rude.  
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1
1
0.18 ... Talking of which, don't reflexively double-click to call that  
unbelievably exotic DX station you just decoded - wait for another  
transmission to double-check his callsign, meanwhile looking him  
up on QRZ or Google. If it seems too good to be true, it is quite  
likely a false decode, ”CQ XIXIMARIA” for instance, or “7T4W?0D  
A+ O2”, or “ 8WL??GN10S77”! That said, there are some weird  
and wonderful novice and special-issue callsigns QRV on FT8, so  
don’t dismiss them all as freaky decodes. [Thanks John NA6L.]  
The educated AP (a priori)  
guesswork that can help  
dig out deep deep decodes  
is more error-prone than  
the usual decoding so  
you’ll see more exotica if  
you enable AP decoding.  
0.19 Tail-ending with FT8 is a bit awkward: first type the DX callsign into  
the DX Call box and click Generate Std Msgs to set up the appropriate messages (or double-click  
the DX station’s CQ message and quickly hit Halt Tx to abort your  
If you find your Tx being  
transmission if now is not the perfect time to call). Remain on your  
carefully chosen clear Tx frequency to call and make the QSO (Hold  
Tx Freq should be selected, remember): if you start calling the DX  
off-frequency then suddenly shift your Tx to his frequency (simplex)  
when he calls you, you will be joining the big red blob of other  
callers, causing QRM.  
pulled” around on each  
QSO, select Hold Tx  
Freq to stay put.  
1
1
0.20 In a DX pileup situation, a shortened message sequence helps maximise  
the QSO rate. To set things up for this, double-click message Tx 1 to skip  
it (it will be greyed out). Now when you double-click a decode to call  
someone, you will start with Tx 2 instead i.e. sending both callsigns plus  
the report, rather than both calls plus your grid. Next, double-click Tx 4 to  
toggle from the conventional RRR message to RR73, short for ‘Yup, got it,  
thanks, let’s end the QSO right here: there is no need for us to swap 73’s  
as well. Good luck with the rest of the pile, CUL, please QSL on LoTW...’.  
Toggling works on  
Tab 1. If you use  
Tab 2, switch to  
Tab 1 to toggle Tx  
1
before returning  
to Tab 2.  
0.21 Shortening QSOs is a contentious practice, raising numerous intertwined issues:  
The protocols for making QSOs (digimode QSOs particularly) are only partially defined and still  
evolving, and anyway the protocols are not universally agreed and followed in practice.  
Some hams send RR73 just once at the end of a QSO and evidently (for various reasons) aren’t  
bothered whether the other party receives it or not. Too bad, that’s their choice.  
Some hams send RR73 repeatedly, anticipating a response, and a few of them get upset if they  
don’t receive it. Too bad, that’s their choice too.  
Some hams send RRR once or repeatedly in the same way as RR73, and may or may not follow  
that with a final message, that may or may not contain the string 73, and may or may not be  
automatically logged (yes, a load more uncertainty there).  
Some messages are sent but not received due to the vagaries of radio propagation, technology  
and gremlins. This point, at least, I think we can all agree on!  
Some dogmatic hams have fixed/definite ideas about what constitutes a QSO and hence may  
or may not log QSOs that others believe complete. Too bad, that’s just how it goes.  
Some amateur QSOs are technically incomplete, for example relying on non-amateur back-  
channels or databases or guesswork to pass QSO information that was not successfully passed  
on-air to the satisfaction of all parties. We’re exploring the limits of radio technology here.  
Logged QSOs may or may not match if submitted to LoTW, Club Log, QRZ or other online logs,  
depending on a multitude of factors, many of which are beyond the control of the individuals  
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concerned. Aside from checking for matches in real time, insurance QSOs are an option … but  
a few hams bitterly resent duplicate QSOs. It’s a no-win situation.  
Generally, we can’t tell for sure what our QSO partners are thinking unless they tell us (which  
is unlikely to happen on-air during an FT8 QSO) hence we can only guess at their position re  
ending and logging and confirming a QSO. ‘Good practice’ is not fixed or guaranteed.  
Some hams see red if someone else dares to express differing opinions to them and appear  
intransigent or intolerant, coercive even. A few  
come across as belligerent bullies or trolls.  
I’ve noticed some regular FT8 users  
Some hams are simply bewildered by the whole  
thing, don’t understand the issues or really don’t  
care since, after all, it’s only a hobby. C’est la vie!  
Instead of complaining, work more DX.  
transmitting on low audio frequencies  
at or even beyond the left edge of my  
waterfall, while few use high  
frequencies near the right edge, so I  
may shift my VFO down by about 100  
Hz from the usual dial frequencies.  
Editing the default frequencies for  
each band is another idea.  
1
1
0.22 The default FT8 frequencies are suggested, not  
mandatory. Aside from DXpeditions using other  
chunks of the HF bands to separate their pileups from  
the regular users, JS8 users are using separate chunks  
too, and FT4 as well.  
0.23 Stretch the waterfall graph to display the full FT8  
subbband out to about 3000 Hz, and open up the  
filters in your radio. The entire displayed region of  
the spectrum should normally show a similar  
background colour: if there are dark patches to the  
left or right, your radio is probably attenuating low  
or high frequencies, making it less likely that you  
My K3 automatically resets the filter width  
whenever I change bands or radio modes.  
It’s worth stepping through each of the  
FT8 frequencies, checking that in DATA  
mode the filter is wide open (to 4000 Hz  
on mine) and centred correctly (at 1500  
Hz) on every band.  
2
3
will decode weak stations there .  
1
0.24 Why do we use “RR73” instead of “R73”? Good question!  
One R is sufficient, but the two R’s plus two decimal digits  
make a string in the same format as a grid square, hence the  
FT8 coding scheme that normally passes grid squares using  
the minimal number of digital bits can handle RR73 in the  
same way, as if it were a grid. If instead you edit the text in  
message Tx 4 to R73, that change turns the message into a  
free-text message type with a limit of 13 characters in total …  
which is often insufficient to pass both callsigns plus the  
space and R73. We’re left with a paradox. Question: “When  
is RR73 shorter than R73? Answer: “When we are counting  
bits in FT8”.  
Since many of us are using QRP,  
it might be nice to use RR72 to  
indicate that, in the same way  
that some QRPers sign-off QRP  
by  
exchanging 72’s. It might also  
remind others to keep their  
power down, where possible.  
That would however require a  
change to the software.  
legacy  
mode  
QSOs  
23  
Selecting the “flatten” option – one of the controls under the waterfall - makes the spectrum appear more even but decoding  
is unaffected (I believe). It’s just eye-candy.  
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0.25 This curious series of t h r e e s p a c e d - o u t M S K s i g n a l s followed by a steeply-sloping  
strong FT8 signal on my waterfall  indicated someone had a serious problem with their  
transmissions, so serious in fact that they were undecodable, hence I wasn’t able to contact them  
to let them know.  
Shortly afterwards, they went QRT. Maybe there was a whisp of smoke …  
1
0.26 Hardware devices of all sorts are identified and handled at a low level by Windows. Windows  
provides Application Programming Interfaces through which drivers access the devices, and the  
drivers, in turn, are used by application programs to do stuff. That’s a complex and problematic  
arrangement. Device drivers are privileged yet bug-prone (raising security concerns) and can  
conflict. Windows selects ‘default’ devices (generally whatever was most recently connected) and  
hides devices from us that it believes are no longer attached, while at the same time retaining the  
associated drivers allowing them to spring back to life instantly if they are ever reconnected.  
Application  
programs  
sometimes insist on using  
devices that are no longer  
physically present. To spring-  
clean your devices, open  
Control Panel, right click  
Device Manager and select  
Run as Administrator. In the  
Device Manager menu click  
View then Show Hidden  
Devices  Expand the device  
tree by clicking the small arrow  
next to, say, Audio inputs and  
outputs or Ports (COM and  
LPT). One-by-one, right-click  
any devices that are no longer  
needed and select Uninstall. If a window shows up with a check box to delete the driver, do not  
check this box as the driver might be needed for another device: uninstall the device only. Reboot  
then check that unwanted devices are gone. [Tnx tip Bruce N7XGR]  
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0.27 Broken something? No transmissions? There are several possible reasons, so check things  
systematically:  
Is the radio going into transmit? Does the little red  
light glow? Does the power meter indicate any RF  
power out? If not, that’s an issue! Check the PTT  
method section under F2 Settings  Radio  If  
you manually press and hold the PTT button on your  
microphone, or the footswitch or use the front  
panel TRANSMIT button, does the radio transmit  
the FT8 tones during a transmission? If you are using  
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VOX, make sure the radio’s VOX sensitivity is high enough to trigger reliably at the audio level  
you are using, and hold-in for the entire over.  
Talking of audio level, make sure enough audio is reaching the rig from the sound card neither  
too little nor too much. See the section on setting transmit levels for tips on that. If adjusting  
levels doesn’t resolve it, check the cable from the sound card to the line-in or microphone input  
on the radio. Try plugging headphones or PC speakers into the sound card output to make sure  
it is actually generating tones, then figure out why the audio isn’t getting to the radio. Is the  
cable broken? Is it plugged in, to the right places?  
Check for USB devices and hubs that automatically power themselves down due to apparent  
inactivity. This function may be a useful power saver  
but it is generally just annoying when sound cards or  
rigs mysteriously disappear from the system. Using  
Windows Device Manager, deselect “Allow the  
computer to turn off this device to save power” for  
each of your USB devices and hubs ▼  
Also in Power Options under Control Panel, disable the  
USB selective suspend ►  
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0.28 Broken something else?  
No decodes? You’ll  
probably find that the  
program is not dead, just  
resting. Check these :  
(A) Set to FT8 mode [tnx  
tip Jacky ZL3CW].  
(
B) Rig on an FT8  
frequency, on a band  
that is open and  
active, in data or USB  
mode.  
(
C) Monitor enabled  
button bright green).  
(
(D) Sufficient audio  
reaching the software.  
The  
tricorder  
thermometer  
indicator  
thing on the left  
should also be green  
with the level around mid-range or higher when the  
band is busy.  
Do you see a smattering of yellow  
and red blobs on the waterfall? Is  
Also check that the CPU is not overloaded: is your the rig on the correct mode and  
computer underpowered? Isolating and decoding FT8 antenna? Can you hear the  
signals takes quite a lot of processor oomph. If there weeeeeee of FT8 signals on your  
aren’t enough CPU cycles available, it won’t be able to receiver? Is the rig on? FT8 is a  
decode and display messages. Time to upgrade?  
weak-signal, not a no-signal mode!  
1
0.29 The stock DXing advice to LISTEN, LISTEN, LISTEN  
applies equally to FT8 and other digimodes, well almost: I normally have the Rx audio turned right  
down, the headphones sitting on the desk, so the digimode version is WATCH, WATCH, WATCH.  
Learn to interpret the waterfall and decodes to figure out what’s  
JTalert and some logging  
happening. Are the DX stations CQing, searching-and-pouncing, or  
programs can highlight  
just quietly monitoring the band (in which case they may appear on  
new DXCCs and new  
PSKreporter, and if you call them speculatively they may just  
grids as they appear in  
respond!)? Notice how the signals grow stronger (redder) as you  
the decodes.  
turn your beam towards directions where there is better  
propagation. Magic!  
1
0.30 Call patiently. If someone is QRMing you, you may struggle to make or complete a QSO until they  
stop. After 2 or 3 failed calls, try shift-clicking your Tx to a different clear frequency and continue  
calling. If that still doesn’t work, maybe your signal is just a little too weak, so try turning your  
beam, or wait until conditions improve. Hey, that’s DXing.  
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0.31 The waterfal settings take some trial and error to  
customize for your system, screen, eyes and preferences. Click to select a slider then use the  
Please read the user guide for details on the waterfall keyboard arrow keys to make fine  
controls, and bear in mind that some changes are instantly adjustments: it’s easier than  
obvious while others only become apparent later as the dragging the slider with the  
waterfall is re-painted under various band conditions.  
mouse.  
0.32 If a stalker is pestering you for a QSO, constantly calling but  
never sending you a report when you respond, or perhaps having started a QSO repeatedly sending  
the same message over and over and over like a stuck record, here are a few things you can try:  
Be tolerant. It is not easy to master FT8! The caller may have accidentally unselected Auto Seq  
and neglected to select the next message manually, and may not even realise he is causing  
problems. Hopefully he will soon catch-on. Perhaps he is distractedly reading the help file or  
looking up these very tips ... well, we live in hope! Try sending a free-text message such as  
“NEXT MSG PLS” or “CHK AUTO SEQ”.  
Be patient. It is possible he is persistently sending the same message simply because your  
acknowledgements are not getting through (e.g. your signal has dipped down in QSB or QRM),  
so the next message is not appropriate. Personally, I’d give at least 2 or 3 repeats, up to 10 if  
I’m keen to complete a DX QSO, especially if conditions are poor and signals are weak.  
While you wait, browse to Time.is to double-check that your computer clock is set accurately,  
especially if this is a frequent occurrence. Is your NTP software running? If you are using  
Meinberg, under the Windows Start menu, select Meinberg then Network Time Protocol, then  
click the Quick NTP status to display a text listing of the time servers it is using. Are there any  
error messages, or is it all normal? The offset (time error) should typically be just a few  
milliseconds e.g. somewhere between +2 and -2, as here ▼  
Check your beam heading and power: perhaps your signal is simply too weak for the stalker to  
decode. Try beaming directly at him (short or long path) and maybe give it a few more watts.  
Open boiler door, add anthracite. Tweak your dilithium crystals. Do the DX waggle dance.  
Conversely, deliberately beam away from the stalker and turn your power down, in the hope  
that having noticed you disappear from his waterfall, he’ll crawl away to his cave while you  
continue working other people.  
Take a break: maybe someone else is transmitting on top of you. Skip a transmit period to check  
whether your Tx frequency is deserted without you.  
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Shift-click (WSJT-X) or right-click (JTDX) your Tx elsewhere on  
the waterfall. If all that achieves is to drag the stalker to your  
new frequency (probably because he has unwisely chosen not  
to select Hold Tx Freq) and he is still not responding to you,  
Last resort: give up!  
Change mode or band.  
QRT. Make a cup of tea.  
Walk the dog. Stroke the  
the online help. Hug a  
st  
QSY again but this time toggle the Tx even/1 option to swap  
periods, transmitting your CQs at the same time as the stalker  
is plaintively calling you. Maybe before long when he notices  
that you have disappeared from his waterfall, and stops to  
listen for once, he’ll see you already making QSOs with other  
savvier hams, and the penny may finally drop.  
1
0.33 New versions of WSJT-X and JTDX install themselves with new Windows start menu shortcuts,  
leaving the old shortcuts there, cluttering up the place. To Spring-clean your start menu, open File  
Explorer then copy and paste the following string into the address box:  
%
ProgramData%\Microsoft\Windows\Start Menu\Programs  
You may see something similar to this  The redundant  
JTDX entries are directories containing shortcuts to  
nowhere. With admin rights, I simply delete them apart  
from the current version  although even that could go too  
as I normally use a desktop or taskbar icon to launch JTDX,  
not the start menu. For bonus marks, create a desktop  
shortcut to that directory to make it easier to find again.  
1
0.34 Don’t get too carried away with the custom messages and  
shortcuts. There is clever programming under the hood to  
optimize communications with the standard messages in FT8,  
which means some compromises. On top of that, you only have  
It is worth composing and  
storing few free-text  
messages in the Tx 5 quick-  
a
select list (under F2 Settings  
1
3 places to fill in each free-text message from a very limited  
Tx Macros) especially if  
like me) you are not an  
accurate typist under  
pressure e.g.  
character set (just numerals, capital letters, spaces and a few  
(
2
4
punctuation characters) . In particular, you will soon discover  
that most users are reliant on Auto Seq, which is easily confused  
by anything out of the ordinary.  
Custom final messages are less of an  
Try it! There’s more  
to the hobby than  
swapping calls, grids  
and reports!  
issue though.  
Free-text (Tx 5)  
messages containing “73” normally  
trigger Auto Seq to realize the QSO is  
over and should be logged - although  
clued-up and patient ops can  
and perhaps TNX TIPS GARY  
continue conversing using 13-character free-text messages  
indefinitely, holding back on the 73 until the conversation is  
about done.  
24  
The JT-mode character set consists of A-Z, 0-9 and the characters + - . / ? and space. The characters @ # < and > have special  
meanings and are not transmitted. They are reserved for testing or otherwise as described in the WSJT-X User Guide. The  
slash is best avoided except as a callsign separator, although it and the full-stop (period) let us send short URLs. Use a redirector  
to shrink longer URLs down to less than 14 characters e.g. BIT.LY/FT8OP  
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0.35 Composing short yet meaningful TXT-like free-text messages in the time available requires  
thought, skill, dexterity and luck. JTDX has an annoying tendency to revert Tx 5 to the default 73  
message without warning, callously wiping out whatever cunning phrase I had composed and  
intended to send, if it needs to re-send one of the previous messages. At the crucual moment,  
TNX M8 73” becomes “ZL7DX ZL2IFB 73” and I’ve missed my chance to send a custom greeting to  
a pal. So, keep an eye on the screen … and be lucky.  
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1
0.36 Once you have things set up, maximise use of your screen and minimise the  
temptation to fiddle with the settings by hiding the  
waterfall controls and menus. Simply clear/unset these  
two boxes ◀ ▶  
0.37 With so little information exchanged in each 15 second over, a sequence of even the most efficient  
and succinct QSOs in FT8 hardly qualifies as running - more of a jog. The pace is easy enough once  
you get the hang of it (it took me a few hundred FT8 QSOs). Here’s a screenshot during a leisurely  
3
0m jog one ZL evening ▼  
I started by finding and then CQing on a clear frequency with Auto Seq and Call 1st both selected  
as usual. The program automatically responded to a decoded caller, taking us through the  
conventional sequence of overs until the Log QSO pane appeared when I received a 73 message  
signalling the end of the QSO. All I had to do then was click the OK button to log the QSO then  
click the Enable Tx button to have the program re-start CQing after it had finished sending my 73  
message. If another caller called me (before or after my CQ), Auto Seq generated the standard  
messages and started a QSO with them. Meanwhile, I was easily able to work, catch up with  
emails, browse QRZ.com etc. on the other screen on my dual-screen Windows desktop.  
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0.38 Are you as confused as me over whether a station is transmitting on the odd or even timeslots? If  
you normally start a QSO by double-clicking a decoded CQ call, it doesn’t matter: WSJT-X  
automatically selects the appropriate timeslot in which to call them.  
But what if you want to call someone who is not CQing, perhaps just  
finished working someone else? What if you start calling someone but  
JTDX colour-codes  
the time box and  
they disappear without a trace? It’s worth checking that you’re odd/even selector to  
transmitting in the correct even/odd period, not doubling with them.  
Mike W9MDB pointed out a simple way to tell is to look at the final digit  
make it even easier.  
of the timestamp for their transmissions: if the times end in a zero, they are using the even slots,  
so we need to call them on the odds. Times ending in 5 indicate they are odd (!). If that’s still too  
st  
hard to figure out in the heat of the moment, here’s a Hinson tip. Simply make sure the Tx even/1  
selector resembles the last digit of the timestamp e.g. if it is 5, the selector box should be filled like  
this , if zero the selector box should be empty like this :  
Maybe you nudged the  
big knob. Maybe the  
software kicked the CAT.  
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1
0.39 Keep an eye on the waterfall. If you notice FT8 signals shifted towards the left or right side, check  
that your rig’s VFO frequency is correct for the band you’re using.  
0.40 If you find yourself sending many repeated messages and failing to complete QSOs because the  
other stations disappear or abandon you to work someone else, you may not have enough  
radiated power. If your signal is too weak, other people will get partial copy and will miss some  
decodes. Experienced DXers will hopefully notice that your signal is weak, and will patiently persist  
as long as you are trying to complete a QSO … but inexperienced or impatient DXers tend to give  
up too soon when conditions are tough. So, the answer is:  
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Make sure as much of your generated power as possible is actually radiated  ideally with a  
short run of low-loss feeder and an efficient well-matched antenna (no need for an ATU). If you  
want to work DX, you will do best with an antenna that has a low angle of radiation such as a  
quarter wave or half wave vertical, a fullwave loop, or an inverted-L or T (top-loaded vertical)  
or of course some sort of beam (the hexbeam for example – small, lightweight, works well).  
As a bonus, a good DX antenna will increase the strength of DX signals you receive, so there will  
be more DX on your waterfall to work!  
Make the best of conditions and propagation. As you change bands, notice whether the  
waterfall is ‘lively’, busy with loads of signals, or ‘quiet’, or ‘dead’. It takes more luck and often  
more power to work stuff when the band is not in good shape. For this reason, it helps to be  
able to use several HF bands, choosing whichever  
DXing is a bit like fishing  we cast out  
one happens to be the best at the time you are on  
the air.  
many CQ calls to catch the odd DX fish,  
and bagging the occasional ‘big one’  
Rather than just CQing, try calling stronger  
stations, the ones with more red on the waterfall.  
Make full use of the tips in this guide e.g.  
transmitting split on a quiet frequency, at the right  
moment (when someone is CQing or has just  
completed a QSO, not during their QSOs) with  
everything carefully adjusted (e.g. accurate clock,  
audio levels in the green). Some stations won’t  
hear you or won’t want to work you, some will …  
so be prepared to call several stations for each  
completed QSO. This is a normal part of DXing.  
makes it all worthwhile. Personally, I  
enjoy the ‘fighters’ most of all – QSOs  
that are challenging to make due to  
poor conditions, QRM etc. are all the  
more satisfying to complete and log.  
It’s a real achievement! The fisherman  
is just as important as his tackle: every  
time we get on air is a chance to  
practice and hone our skills,  
occasionally trying new tricks. It’s not  
only about bagging the catch  enjoy  
the chase!  
Be patient and persistent yourself.  
FT8 is designed specifically for propagation conditions such as multi-hop  
sporadic-E at 50 MHz circumstances where signals are weak and fading,  
openings short, and quick completion of reliable, confirmable contacts is  
particularly desirable.”  
Development”, K1JT, K9AN and G4WJS, QST November 2017  
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FT8 Operating Guide  
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0.41 Setting the dead green goalpost Rx marker to  
monitor a specific DX station can be awkward:  
If you can find him on the waterfall, simply click  
the left edge of his signal – that’s the easy bit but  
quickly locating his signal on a busy waterfall can  
be tricky.  
Double-click to select the  
numbers in the Rx frequency  
the  
frequency numbers using  
the numeric keypad, ending  
with Enter or Return.  
Alternatively double-click one of his decodes to set up  
your messages and start calling him (unless you hurriedly click  
Halt Tx).  
box,  
then  
type  
Or type the audio frequency listed on his decodes into the Rx  
2
5
frequency box on the main WSJT-X or JTDX screen or if you  
are close, click the up or down arrows to fine-tune ►  
1
1
0.42 While you are CQing and waiting for a response, keep an eye on the decodes for DX callsigns on  
the left. You won’t decode DX stations that are transmitting at the same time as you, but you may  
decode their callers during your reception periods.  
0.43 If you need a QSO with someone who is calling CQ to a different area, pick one of these:  
Call them anyway, once or twice, on a different frequency (split) so as not to QRM any callers  
they may have from their target area. Don’t call them continuously, especially not simplex.  
Instead of calling them specifically, make directed CQs to their area in the hope that they will  
see you and respond to you if they wish.  
Patiently wait and watch. If they stop CQing, or drop the specified target, pounce: call them!  
1
0.44 With so much going on, especially when the band is busy, I sometimes got confused  
over who I’ve just worked and logged. Thanks to an idea floated on the WSJT reflector,  
I wrote a simple batch file to call Windows PowerShell to display the last few QSOs from  
the WSJT-X log, updating itself as each new QSO is logged. With the black and grey  
PowerShell window shrunk down to just a narrow strip at the edge of the screen, it  
shows the callsigns I have most recently logged ►  
To do this for yourself, the Windows PowerShell command line is:  
powershell.exe get-content %LOCALAPPDATA%\WSJT-X\wsjtx.log -tail 3 -wait  
Courtesy of VE2EVN, the Linux equivalent is:  
JTDX shows us the last callsign  
tail -n 3 -f ~/.local/share/WSJT-X/wsjtx.log  
“Logd” on the lower status line ▼  
25  
The text “Rx” and “Hz” currently within the frequency setting white boxes should really be outside the boxes. That simple  
change would make it even easier for us to click or double-click anywhere in the box and enter the audio frequency number,  
without having to worry about the Rx and Hz text also being selected.  
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0.45 WSJT-X routinely writes a WAV file of  
1
received audio to disk while it processes it.  
Even if you configure WSJT-X not to save  
its WAV files using the obscure option  
None” under F2 Settings Save , it still  
does. The reason is that normally the WAV  
file is deleted automatically by WSJT-X  
about 10 seconds after the processing is  
completed (giving us time to save it if we  
decide to do so). However, when you exit WSJT-X,  
the current WAV file is abandoned, remaining  
orphaned on disk. If you start and stop WSJT-X  
repeatedly, you’ll eventually discover an orphanage  
full of abandoned WAVs, cluttering up your hard  
drive. Some users have reported hundreds of  
orphaned WAVs.  
It’s worth clearing out the orphans from time to  
time, either manually (using the housekeeping  
function on the File menu ) or using a simple batch  
file with the following Windows command line  
del %LOCALAPPDATA%\WSJT-X\save\*.wav  
1
0.46 If you change your mind or mess up your  
typing while hurriedly editing the free-text  
message Tx 5, you can instantly reset it to  
the standard 73 message by double-clicking  
the Tx 5 box  but be careful about  
precisely when you do it: annoyingly, the  
double-click also changes immediately to  
sending that message if you are  
transmitting a different message at the  
time, and offers to log the QSO.  
0.47 Show the grids you’ve worked on a Google map using an online  
mapper by WG7J. The mapper accepts ADIF log files up to a certain  
to pre-process it using this grid extractor utility by W9MDB to  
generate a much smaller ADIF containing just one QSO per grid.  
Green grids are confirmed, reds aren’t, yet. Mouse over for info.  
Note: some hams give out and may even confirm the wrong grids ►  
It is fairly obvious when their grids put them in the sea, unless they  
were /MM at the time. Or swimming. Walking on water perhaps.  
Do us all a favour: double-check your own grid square, please,  
especially if you are confirming it via LoTW.  
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1
0.48 What constitutes a valid, complete QSO is another zombie topic, one that has been raised,  
discussed, kicked around and buried on the WSJT reflector many times. Cutting to the chase, there  
is no consensus among the ham community on this … hence when we are in QSO with someone,  
we don’t know which way they think. Some of our QSO partners will steadfastly insist on  
exchanging 73s with us, some won’t even send 73s, and  
If you believe a QSO is complete,  
quite a few more are in the ‘don’t care either way’  
bracket. A few don’t even bother logging their QSOs (license  
log it and hope that the other  
guy also logs it. If you believe  
conditions notwithstanding). Specifying and coding the  
your QSO is incomplete, wait  
software for such ambiguity on the part of the people we are  
and hope that the other guy  
contacting is, let’s say, challenging. Even if we were able to  
keeps on trying to complete as  
set our own preferences with a tick-box somewhere, we still  
long as you, and then logs it.  
don’t know what’s happening at the other side of the QSO,  
so it’s left to the operator. Personally, I consider my QSOs complete when we have made a  
connection sufficient to copy each other’s callsigns and exchange a few more bits of information  
such as our reports. On FT8, when I’ve sent an RRR or RR73 message, I log the QSO.  
1
0.49 Different amateurs sharing the same station can set up personal WSJT-X or JTDX profiles to suit  
themselves, using the -r [name] command line modifier originally intended for using alternative  
rigs with different settings. [Name] is just a handy label for the profile, such as the callsign (no  
spaces).  
For example, if I launch WSJT-X using WSJT-X -r ZL2iFB  
it sets up a environment just for me, with a ZL2iFB  
subdirectory to hold my ADIF log, ALL.TXT and .WAV  
files, plus the .INI configuration file holding the default  
settings which I would then customize to suit my  
preferences (or more likely copy across from the  
unnamed profle I already have). It reminds me that I  
am using a custom profile for ZL2iFB by showing that  
name on the window title.  
If I close WSJT-X and then re-launch it using WSJT-X -r  
ZM4T, it sets up another environment for the club,  
with its own log, WAVs etc. in a separate ZM4T  
subdirectory. We can then choose between the two  
setups whenever we launch WSJT-X, with any config  
settings being saved to the respective profile.  
The easiest way to choose between profiles is to  
append the -r [name] modifier to the Target for the  
icon that launches WSJT-X, renaming the icon  
accordingly ►  
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1
0.50 Does RF get into your computer and mess things up  
when you transmit? The ideal solution is to reduce  
the amount of RF in the shack, for example by siting  
and feeding your antennas some way away using  
balanced line, or good quality coax with a balun or  
choke at the feedpoint of a balanced antenna.  
While you mess around with earthing,  
baluns and chokes, order some well-  
shielded USB cables with copper braid  
giving more than 95% coverage. Gold- or  
silver-plated contacts, and maybe a few $  
Earth bonding at the shack end can also help, as  
well as running QRP.  
more,  
suggest  
above  
average  
performance for USB cables, and audio  
cables too for that matter. Don’t bother  
with Oxygen Free Copper though: last  
time I checked, plain old copper conducts  
very nicely, thank you. I have no problem  
with my timbre and sound field.  
If that’s not enough, try putting suitable ferrite  
chokes26 on the PC cables. Split-core clamp-on  
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7
chokes are easy to fit . Physically routing the  
cables, and perhaps re-siting the whole computer,  
further away from your radio, amp and feeder may  
In JTDX, there are additional autosequence  
options to determine how the system responds  
to callers. Look under AutoSeq on the main  
menu bar and feel free to experiment ►  
AutoSeq3 (“Call based on end of decoding”) suits  
me. I prefer “Max distance instead of SNR” to  
respond to more DXey callers first, and I’m  
perfectly happy to work people more than once:  
I’m friendly like that.  
1
0.51 If you use a dual-monitor setup with WSJT-X  
running on one monitor, leaving the other for  
logging and other stuff, WSJT-X usually  
remembers but sometimes forgets which  
monitor it belongs on when it launches. It’s  
annoying to have to drag or Windows-arrow it to  
the other monitor each time. Fixing that  
annoyance is a bit hit-and-miss. Here’s the trick that works for my USB-connected second monitor:  
Temporarily disable the second display in Windows Device Manager.  
Launch WSJT-X. It should open on the working display.  
Re-enable the second display in Device Manager.  
Drag or windows-arrow the WSJT-X main window and waterfall to the other monitor.  
Close and restart WSJT-X to check that it has got its monitor memory back. If it hasn’t, you’re  
on your own, sorry!  
2
6
L L  
Choose an HF-rated ferrite mix with an A value of at least 2,000 to add enough inductance. With A values in the low  
hundreds, VHF-rated ferrites are cheaper (often free!) but add little impedance at HF.  
The larger HF-rated cores, including man-sized circular toroids, are better as you can pass the cable through them several  
27  
times. The choking inductance increases in proportion to the number of turns squared e.g. 2 turns have 4 times the inductance  
of 1 turn. Use thin, flexible cable with small or no connectors to squeeze more turns into a given core.  
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1
0.52 Most of us choose to upload the callsigns and locators we are decoding to PSKreporter.info, where  
they can be flagged on a map. The PSKreporter screenshot  for instance, shows roughly 25  
yellow blobs - FT8 stations across South America, Africa and Europe being received by a German  
The map is dark because this was in the wee small hours of his morning … when he wouldn’t  
normally expect to be working DX on the high bands.  
“The duties of a travelling watch inspector for a big railway system are  
much more arduous than one might imagine. One system pays $18,000  
per year for this purpose only. It takes the assistant inspector two years to  
visit all the inspection points on the lines and each test of a watch lasts 72  
hours. If it varies six seconds in that time, it is rejected.”  
[
Popular Mechanics, January 1905]  
[
In today’s money, $18k is worth about $½m]  
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FT8 Operating Guide  
11 Special callsigns  
1
1.1 Deep within the technical specification of the FT8  
protocol itself, the format of “standard callsigns is  
defined quite specifically and narrowly . This  
reduces the variety of callsigns that the protocol  
needs to handle, hence limiting the number of digital  
bits required to code them. However, some special  
event, compound and commemorative calls are so  
A standard amateur callsign consists  
of a one- or two-character prefix, at  
least one of which must be a letter,  
followed by a digit and a suffix of one  
to three letters. Within these rules, the  
number of possible callsigns is equal to  
somewhat over 262 million … Since  
is more than 268 million, 28 bits are  
special” that the original FT8 protocol simply could  
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8
2
not accommodate them within the 28 bits reserved  
for callsigns in most of its messages (e.g. CQ calls,  
reports and RRR or RR73 messages)  
enough to encode any standard callsign  
uniquely.” [WSJT-X User Guide]  
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1
1.2 Although special callsigns of up to 13 characters can be included in free-text messages, they are  
not interpreted as callsigns: they are simply arbitrary text strings. If someone double-clicks one of  
those decoded free-text messages from some exotic DX in the hope of calling them, they would  
be out of luck, even if the free-text message includes “CQ”. The software does not know what to  
do with the message except display it to the frustrated user! It does not automatically enter the  
full callsign in the DX Call box, nor does it include it in the generated messages for their response  
due to the bit-shortage.  
1.3 Standard callsigns with some  
conventional location modifiers  
(
e.g. typical CEPT-type compound  
calls with ITU standard/DXCC-  
approved country prefixes followed  
by a slash) are handled by the  
software, passing the full callsign in Tx  
1
and Tx 6 but only the home callsign  
part in the other messages. If I were  
to nip over to, say, Auckland Island,  
my callsign might be ZL9/G4iFB so my  
generated messages for a typical QSO  
would be these  Notice that the  
ZL9/ prefix is only sent in my Tx 6 (CQ)  
and Tx 1 (initial response to caller) messages. The list of  
prefixes and suffixes that are treated in this way is  
available from the Help menu on the WSJT-X main screen  
Other uncommon situations are  
not explained in the help e.g. if a  
station has both a prefix and a  
suffix, or if two compound-call  
stations are in QSO. Perhaps you’d  
care to experiment to find out what  
happens, in which case please let  
me know how you get on.  
(
with Menus selected). Those specific “type 1” prefixes  
and suffixes (about 350 of them) are encoded and sent in  
as few bits as possible, allowing two full callsigns to be  
included in some generated messages. Some unlisted  
type 2” compound callsigns (such as /M, /MM and /W3)  
may be sent without the other callsign in some messages.  
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1
1.4 According to Claude Shannon’s information theory, the total number of digital bits in the payload  
determines the amount of information that can be conferred by an individual message. In 77-bit  
FT8, callsigns can be compressed down to hash values which are transmitted, then expanded back  
2
8
to callsigns on receipt . However since the compression routine is lossy, at the receiving end  
there are several possible expansions of a given hash  so which is the correct callsign? The answer  
is found by checking back through recent decodes to find the callsign that was transmitted in full  
at some prior point, and which gives a matching hash value. You may notice this process  
happening from time to time  
as the hashed callsigns may be  
shown in angle brackets ►  
Notice that, in that particular  
example, DL7ACA  a perfectly  
ordinary and conventional  
German callsign has been hashed to reduce  
the number of bits required because the  
other callsign in that message, SX60RAAG, is  
special and needed more bits. Either callsign  
Hash collisions (where different callsigns  
compress to the same hash values) are a  
possibility, along with CRC and AP failures. If  
you see a truly bizarre callsign (not merely  
may be hashed.  
special), it is probably a bust.  
1
1.5 Here’s an example of the hashing  
process at work ►  
Having just  
launched JTDX and tuned to a DXcluster  
spot for 9LY1JM on 17m, the first seven  
decodes all displayed the <…>  
placeholder in place of the DXpedition  
callsign, indicating that the callsign was  
being passed as an as-yet-unrecognised  
hash code.  
Subsequent decodes showed 9LY1JM’s  
callsign after someone had sent the  
DX callsign in full, hence JTDX was able  
to hash it and match up its hash value  
with the hash value sent by other callers, displaying the corresponding DX callsign for me rather  
than <…>  
1
1.6 Hashing isn’t a precise method to pass callsigns. Hash values are ambiguous. If, coincidentally,  
two or more callsigns with the same hash values are both active, the software may choose and  
display the wrong one. The software should always send the sender’s full callsign un-hashed at  
least once in a QSO in order to be crystal clear, although it may need to hash the other callsign in  
the message to save bits.  
2
8
Hash codes for special callsigns are calculated and cached as they are received, ready to match against any subsequently  
transmitted. When WSJT-X is closed, the cache is cleared and it takes a while to rebuild the cache after it restarts.  
29  
Not 9LY1JM themselves, unfortunately, since I could not copy them! The software can hash either callsign in the two-callsign  
messages, so by chance someone must have sent a message containing a hash of their own callsign with the DX callsign in full.  
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1.7 Hovering the mouse over the Tx 1  
1
button in WSJT-X pops-up an  
ambiguous message stating that  
toggling Tx 1 is ‘not allowed for type 1  
compound call holdersbut the user  
can press ahead and skip Tx 1 anyway.  
The pop-up message is in fact an  
instruction, not a statement of fact.  
Not allowed’ actually means ‘Do not  
do this’. Don’t do it!  
1
1.8 If the operator foolishly ignores the  
instruction, skips Tx 1 and calls a station with A caution to those of us who often bypass the  
a compound callsign using Tx 2, the called Tx 1 message (calls and grid) and start with Tx 2  
station’s Auto Seq responds with Tx 3 which (calls and report). If you are calling a DX station  
omits the call of the station to whom they are with a special callsign, when the DX station  
responding. This is a recipe for confusion responds, none of the messages in his  
when there are several callers, often the case transmitted sequences will have your callsign in  
since compound calls tend to be DX them. There is no way to know for sure that the  
travellers. Regardless of whether our callers DX station is responding to you or another  
send Tx 1 or Tx 2 at us, and regardless of station. The fix, when calling stations with  
what kind of callsign we are using, we should special callsigns, is always to start with Tx 1.”  
always respond with the caller’s callsign in  
[Rick K1HTV]  
our first message to be clear who we are  
3
0
working .  
1
1.9 The same issue affects both parties to a QSO involving a special  
callsign. Stations with special callsigns who skip Tx 1 when calling  
other stations may be frustrated to discover that their Tx 2 messages  
are mostly ignored. The reason is that their special callsign gets  
transmitted as a hash code that is displayed as <…> on the receiving  
end unless by chance the recipient’s system happens to have  
WARNING  
Repeat after me:  
do not skip Tx 1  
Do not skip Tx 1.  
Do not skip Tx 1!  
previously received a message containing the full callsign, enabling it to match up the hash codes.  
Recipients see someone repeatedly sending cryptic messages of the form “<…> +10” at them.  
They are unable to respond properly because their systems do not know who to respond to. The  
auto-sequencer robot is quite clever <…> but not bloody clairvoyant!  
3
1
1
1.10 Likewise stations with special callsigns are unable to make contest QSOs on FT8 because the  
contest exchange does not leave sufficient bits to send their special callsigns in full. There simply  
aren’t enough bits available. FT8 falls a bit short sometimes  but not always ▼  
3
0
I believe this is a design requirement for the software. Not doing this qualifies as a design flaw.  
Special callsign holders can still contest using legacy modes with character-wise encoding such as CW, RTTY and PSK. Don’t  
31  
shoot the messenger, or the developers: it is one of the inevitable compromises of trying to squeeze quarts into pint pots. Rant  
at Mr. Shannon or the bit tax. Or apply for an ordinary, common-or-garden, plain, simple and most of all short callsign! ꢁ  
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1
1.11 To explore the way various messages and callsigns are handled in FT8, check out “ft8code.exe” in  
the WSJT-X program directory. Run it from a command line with a message as a parameter in  
quotes to find out how the message would be encoded, sent and decoded. For example, if I  
wanted to send the message “CQ E5/ZL2IFB/P RA01” via FT8, ft8code tells me thats a nonstandard  
call so my message would be transmitted as “CQ E5/ZL2IFB/Pomitting the grid ▼  
This is HF Voyager, an  
experimental scientific  
buoy (a Wave Glider  
solar-powered drone)  
floating across the Pacific  
tracking whales … and  
amusing itself by making  
FT8 QSOs en route under  
the callsign KH6JF/MM.  
Did you work the robot?  
Got your QSL card yet?  
Copyright © 2021 ZL2iFB  
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FT8 Operating Guide  
12 DXpeditioning with FT8  
1
2.1 There are pros and cons to using FT8 on DXpeditions:  
On the upside, it is a popular HF mode, good for DXing even for those limited to low power and  
basic or stealth antennas. It can make short openings and marginal paths productive.  
On the downside, the maximum QSO rate is normally  
A competitive CW, SSB or RTTY  
op on a good station can sustain  
a rate of 200+ QSOs per hour,  
maybe 250 or more for a similar  
level of operator effort - so  
that’s potentially 4 or 5 times as  
many DXpedition QSOs per  
hour using legacy modes.  
about 60 QSOs per hour using the standard protocol.  
In practice, experienced digimode DXers (such as Roly P29RR)  
can sustain a rate of about 50 FT8 QSOs per hour, provided  
they have the ability to concentrate intently on the screen and  
cope with the occasional need for repeats and the sequence-  
out-ofs. QRM and contention for bandwidth would reduce  
the rate still further for very rare and popular DX.  
1
1
2.2 The DXpedition protocol changes FT8 for both the DXpedition  
station (the fox) and their callers (the hounds). A single fox transmitter can generate multiple FT8  
signals simultaneously, and may send messages to two stations in the same transmission (ending  
one QSO and starting the next) on a single frequency, making QSOs with several hounds in parallel  
on one rig and band. Fox rates may approach 400 QSOs per hour, per station!  
2.3 To use DXpedition protocol as a hound (a DX chaser):  
Install, run and configure a recent version of  
WSJT-X or JTDX. Get it running properly, ideally  
with CAT control of your radio using the Rig or  
Fake It settings. Spend some time making normal  
QSOs to familiarise yourself with FT8 operating.  
If you don’t have CAT control, you will  
have to QSY your Tx somewhere below  
1
000 Hz manually after the fox responds  
to your calls. If you don’t QSY, the fox  
can’t complete the QSO with you.  
Add the nominated DXpedition FT8 frequencies  
to the frequency table e.g. 14.090 (not the usual FT8 frequencies!) under F2 Settings  
Frequencies. Right-click the table, then insert the DXpedition FT8 frequencies. Leave the  
usual FT8 frequencies alone (it’s OK to have multiple FT8 frequencies on each band - set up a  
separate configuration for DXpeditions if that helps).  
When the DXpedition is on the air, expand the band coverage of your waterfall to view from  
2
00 to 4000 Hz e.g. using 3 Bins/Pixel and start at 200. Although your rig’s bandwidth may not  
cover the entire range, with CAT control you can shift-click the waterfall to transmit anywhere  
above 1000: before transmitting, the rig will automatically QSY and generate the appropriate  
audio frequencies, QSYing back again afterwards. However, you may then be unknowingly  
3
2
QRMing other callers if your waterfall blanks out towards the right .  
32  
With my K3, the waterfall blanks out just above 3500 Hz, even with the K3 data mode filter wide open at 4.0 kHz.  
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In WSJT-X, select Special operating activity then Hound on the F2 Settings  Advanced tab  
(unless you are the fox on the DXpedition!) ▼  
It’s easier still in JTDX: click the Hound button on the main screen then right-click it to enable  
the auto-QSY Frequency Control function. It even auto-cancels when you revert to the normal  
FT8 frequencies. Nice!  
Left click  
enables  
Hound mode,  
then right  
click for  
HoundFC ▼  
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1
1
2.4 In DXpedition mode, a hound’s Band Activity left hand pane only shows  
decodes up to 1000 Hz, in other words the fox and the hounds he is working,  
unless you have selected Rx All Freqs on the main screen . The fox sees  
them all, of course, and selects them to add them to his queue.  
2.5 In DXpedition mode, most of the usual  
message selectors are greyed-out 33  
,
leaving just two  You will call the fox  
with your Tx 1 message until he  
responds to you, then you’ll send Tx 3  
with your report until he acknowledges  
it. That’s it. No RRR or 73 or custom  
messages are needed from you  keep  
your transmissions to the absolute  
minimum so other hounds have their  
chance to catch the wily fox.  
1
2.6 Point your antenna towards the  
DXpedition and select an appropriate  
power level (typically in the region of 5 to 50 watts – neither so little that you won’t be heard, nor  
so much that the fox pointedly ignores you).  
1
1
2.7 Shift-click (WSJT-X) or right-click (JTDX) to set your transmit frequency (the red goalpost) on a  
reasonably clear column on the waterfall above 1000 Hz.  
2.8 Wait patiently until you see the fox transmitting, generally on the even cycles. You may see his  
single CQ call, or several signals as he makes QSOs with up to 5 hounds in parallel. Fox decodes  
often include concatenated  
messages like this  Here a very  
weak fox is completing a QSO  
with NA7TB and (at the same  
time on  
a
second fox Tx  
frequency), sending a report to K5EK.  
1
2.9 Once you are copying the fox reliably, double-click one of his decodes to set things up and start  
calling him in the normal fashion.  
If you cannot copy the fox, DO NOT CALL HIM as you will simply create QRM and  
aggravation. Even if by some miracle he responds to you, you won’t see his response  
and someone else may miss out on a QSO as he tries to contact you in vain. Try  
turning your beam or using another antenna. Try another band maybe. Do the  
sunspot dance. Or simply wait patiently like a good DXer, watching the screen, poised  
to pounce like a hawk if and when you do see decodes from him.  
3
3
st  
st  
The Tx even/1 option is also unavailable to the hounds: foxes ALWAYS transmit on the even/1 sequences. You will normally  
see lots of blobs on the odd/2nd sequences, but hopefully only the fox on the left of the waterfall on the evens.  
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2.10 In DXpedition mode, a special hard-coded timer automatically disables your transmissions after 2  
3
4
minutes without a response … however, in that time, the fox may have put you on the queue. If  
the fox responds to you later, after your DXpedition mode timer has timed out and before you re-  
start transmissions, your Tx will automatically be re-enabled to send him his report, completing  
the QSO when he acknowledges it with his RR73 message back to you. Use the Tx breaks wisely.  
If necessary, QSY to a nice clear Tx frequency and hope it is clear at the fox end. Adjust your power  
and beam if necessary. Watch the screen. Fiddle  
with the radio. Bide your time. Enjoy the  
moment. Behave yourself. Be an obedient hound.  
1
1
2.11 If the fox responds to your call with his Tx 2 message (your callsign and report), your system will  
3
5
automatically QSY your Tx to a frequency below 1000 Hz to send him your Tx 3 message (both  
callsigns, R and his report). If you don’t have CAT control, you should QSY manually below 1,000  
Hz to make the QSO unless the DXpedition op is alert enough to complete it manually.  
2.12 If for some reason a fox is transmitting on the odd/2nd periods, hounds  
st  
can use control-E to force their transmissions to the Even/1 periods  
st  
even though in WSJT-X the Tx even/1 option on the screen is greyed out  
in DXpedition mode  As well as not being active to select the period, it  
doesn’t show the current status. Use shift-E to return to the odd/2  
n
periods, the default.  
1
1
2.13 Your system will continue sending Tx 3 below 1000 Hz several  
Having initially responded  
times until the fox acknowledges receipt with his Tx 4 message  
to your calls, if the fox is  
(
your callsign and RR73, possibly as part of a multi-transmission  
ignoring  
messages,  
your  
your  
Tx  
3
Tx  
message), concluding the QSO.  
2.14 The fox will send your report up to 3 times before giving up, frequency may be busy with  
logging the QSO and moving on to the next one. This happens other callers causing QRM.  
automatically. So, if you don’t receive an RR73, there’s little Try manually shifting your  
3
6
point continuing to transmit your report incessantly : you are Tx to a different, clear  
wasting time, energy and bandwidth. Stop sending and (when frequency on the waterfall.  
available) check that you are in the online log … or if you are Stay below 1000 Hz though.  
desperate, try again another day, making an insurance QSO.  
34  
Due to a persistent WSJT-X “feature”, the WD timer value remains static in the bottom right corner of the screen in  
DXpedition mode. The normal WD timer is not used. Instead a separate, secret, internal timer is hard-coded at 2 minutes (4  
transmissions). When your 2 minutes baying at the fox are up, the receiving bar does not go red and display “Runaway Tx  
watchdog” as it normally does with the WD timer. The Enable TX button is automatically deselected, loses its red background  
and you stop transmitting. That’s it.  
3
5
6
It does this intentionally to separate you from the other baying hounds. All that yapping would slow or prevent your QSO.  
The fox will see your continued plaintive messages if they are decoded, and he may take pity on you, responding manually  
3
by forcing through what, to him, is a duplicate QSO. However, that may mean the fox ignoring another caller who is not already  
logged, so unless this is your only shot at a rare QSO (an ATNO), stop hounding the poor fox!  
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1
2.15 In Hound mode, information from decodes is not routinely sent out onto your shack network via  
UDP, although once you work and log the fox, the log QSO message is broadcast as normal. The  
usual stream of UDP messages resumes when you leave DXpedition mode … so after you work and  
3
7
log the fox, don’t forget to de-select Hound and tune back to the normal FT8 frequencies  unless  
you are hunting the fox on another band next. Take a moment to celebrate the wonders of weak-  
signal digimode DXing!  
2.16 MSHV has a hybrid multi-transmit mode (called “Multi Answering Auto Seq Protocol FT8"), similar  
but not identical to the DXpedition fox-n-hounds mode. These are conventional FT8 QSOs except  
the DX station/fox makes several at once using separate transmit frequencies. Some DX stations  
have taken to running this way on the normal FT8 frequencies, causing confusion and hogging the  
subband: it would be more considerate of them to shift to a different frequency.  
FT8: Decoding is now spread over three intervals. The first starts at t = 11.8 s into an  
Rx sequence and typically yields around 85% of the possible decodes for the sequence.  
You therefore see most decodes much earlier than before. A second processing step  
starts at 13.5 s, and the final one at 14.7 s. Overall decoding yield on crowded bands is  
improved by 10% or more. (Systems with receive latency greater than 0.2 s will see  
smaller improvements, but will still see many decodes earlier than before.)”  
Email from Joe K1JT to the WSJT-X development reflector, May 2020  
37  
I recommend checking that the Hold Tx Freq option remains selected after entering and leaving DXpedition mode. Due to  
an annoying little bug in WSJT-X, it is silently de-selected.  
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13 Flaws, bugs and improvements  
1
3.1 Flaws or limitations in the design of FT8 and the associated  
software, plus bugs and problems with our on-air operating  
conventions, are coming to light. Most are trivial and can be easily  
overcome or simply ignored. Some are potentially more significant  
blockers, such as:  
Much of this is  
subjective: some of the  
things I call “flaws”,  
“bugs” and “issues”  
others dismiss “as  
designed” and “not a  
problem”.  
Inconsistencies and awkwardness in the user interface,  
especially in WSJT-X (more below).  
Differences of opinion on what truly constitutes a completed, valid QSO, and on how to use FT8  
for contesting.  
Inconsiderate operating such as calling over the top of ongoing QSOs, rudely ignoring directed  
CQ calls and messages, over-driven audio and excessive power for the path, and contention for  
finite band space.  
3
8
1
3.2 There are inconsistencies, limited data-entry validation and other usability issues in WSJT-X such  
as:  
The message selector buttons can be ambiguous ►  
There’s no feedback to the user when entering or  
editing a free-text message that goes beyond 13  
characters or includes invalid characters [solved in  
JTDX].  
Inability to toggle message settings (e.g. swapping  
message Tx 4 between RRR and RR73) without also  
selecting the toggled message to be sent immediately  
[
solved in JTDX].  
Inability to change the Rx frequency while transmitting.  
Decodes are appended to the Band Activity and Rx Frequency window strictly according to  
when they were decoded (on the first pass then the second pass), with no ability to sort them  
by frequency, call, locator, strength or time received.  
New decodes reset the Band Activity window to the bottom, even if we were scrolling up  
looking for a specific decode (the only way to lock the list is to stop decoding).  
The Tx and Rx frequency-setting boxes include the static/boilerplate text Tx, Rx and Hz,  
which makes it a bit trickier to update the numeric values: we first need to select the numbers,  
being careful not to select the boilerplate text.  
Shift-clicking F11 or F12 moves the Tx down or up in 60 Hz steps but (on my system) this stops  
working after WSJT-X has been running for a while. Subsequently, those function keys move  
the RX frequency in 1 Hz steps, regardless of whether I also hold shift, control or alt.  
38  
JTDX is not immune to issues but, in my experience, they are fewer and less annoying than those in WSJT-X.  
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Various auto-sequencing issues including the bouncing ball thing noted earlier and QSO  
hijacking, plus possible inconsistencies in responding when someone answers our CQ with their  
Tx 2 skipping Tx 1.  
The log QSO pane evidently only appears if we send a free-text message containing the string  
“73” … but what if I choose to end my QSOs with, say, “BIT.LY/FT8OP” (the short URL for this  
very document) or “MERRY XMAS” or whatever? If I’m not on-the-ball, there’s a good chance I  
will neglect to log the QSO.  
The “Disable Tx after sending 73” option is ignored if you are using Call 1st. After logging a QSO,  
remember to Enable Tx to start your next CQ.  
Any change to the current Tx 5 free-text message is lost if we open and close F2 settings: it  
reverts to the auto-generated plain [his call] [my call] 73 message.  
In DXpedition mode, fox decodes don’t stand out on the Band Activity pane unless it is a new  
DXCC country. It would be handy if decodes from the fox (i.e. sent by the callsign currently in  
the DX Call box) were highlit in some way, even when he was not actually working us. This  
might be useful also in non-DXpedition mode.  
Various other minor issues (e.g. confusing colours, low-contrast sliders,  
truncated screen-tips etc.).  
1
3.3 These and other concerns, plus test findings (ideally explaining how to  
reproduce bugs on demand), suggested workarounds and improvement  
suggestions in general may be discussed on the WSJT reflector.  
However, despite the splash screen warning message when rc/beta  
versions load  
If you are a UI  
programmer,  
please volunteer to  
work on WSJT-X:  
your expertise is  
sorely needed!  
, if you are  
not  
programmer  
a
willing to get involved in coding User  
Interface changes on a multiplatform  
system, be prepared for your UI-related  
feedback to be ignored or robustly  
rejected: essentially, UI matters are  
unwelcome distractions to the team.  
1
3.4 Users should be able to disable the auto-QSY CQ function intended for VHF/UHF use as it can  
cause the transmitter to QSY unexpectedly, perhaps out of band. For example, imagine a station  
on 1850 kHz sending “CQ 1930 AB1CDE”: if we double-click that message to respond to them, our  
rigs will automatically QSY to 1930 kHz to make the QSO.  
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1
3.5 Technically, FT8 and other digimodes can be fully automated, replacing operator effort and manual  
input with CPU cycles, but that is a step too far for most amateurs, as well as the team behind the  
JT modes: this is, after all, a participative hobby. Watching our stations making QSOs ‘for us’  
reduces us to passive observers. However, one potentially useful application involves setting up  
automated stations on extremely inhospitable DX  
Provided  
the  
licensing  
and  
locations such as Bouvet Island. I envisage futuristic  
DXpeditioners taking robotic FT8 stations with them, to  
sit silently in the corner racking-up rare DX QSOs for the  
duration of the trip … and perhaps beyond ►  
environmental authorities approved,  
self-contained ruggedized solar-  
powered FT8 robots with satellite  
links for logging and control could  
potentially be left behind when the  
DXpeditioners depart, perhaps with  
scientific research and monitoring  
capabilities (like weather stations) to  
justify their continued presence.  
FT8 may also be useful for telematics (e.g. remotely  
monitoring/controlling repeaters and beacons, tracking  
vehicles) and store-and-forward email-like systems  
using long-distance amateur HF radio links, rather than  
VHF/UHF point-to-point, satellite or Internet links.  
1
3.6 Various other enhancements to the FT8 protocol and  
software have been suggested e.g.:  
Using a bit as a flag denoting “Message continues”, allowing free-text messages to be chained  
together on transmit and reassembled on receipt (JS8 uses the ~ tilde character ~ in the  
message text for a similar purpose).  
Combining the audio streams from separate antennas and receivers (diversity reception).  
A simple “go back” function to un-do a QSY, instantly returning to the previous tuned frequency.  
Aside from the substantial effort required to specify, code, test, debug and document such  
changes, there are other issues to consider:  
Complexity: the more complicated the system, the more likely it is to suffer performance and  
other limitations, including design flaws, bugs and operator errors.  
Backward and forward compatibility: step-changes are problematic, hence incremental  
changes are preferred … but that’s not always possible (e.g. the  
At the end of the day,  
change from 75 to 77-bit FT8 forced everyone to upgrade or be  
the developers have the  
left for dust).  
final say in what gets  
Priorities: one amateur’s enhancement is another amateur’s  
drawback. It is hard to gain consensus on the few changes  
actually worth progressing from the many possible approaches,  
especially given the variety of applications for WSJT-X (e.g. EME  
and meteor scatter on VHF/UHF, plus HF DXing).  
implemented and how,  
since they are the ones  
doing the hard graft. It’s  
their ball: we’re just  
kicking it about.  
Take-home lessons for DXpeditioners intending to use FT8:  
1
2
) Request a standard, conventional, short DX callsign if possible; and  
) Try-out the current release of WSJT-X using your (likely) DX call and get  
familiar with running DXpedition mode as a fox well before setting off.  
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14 Close and acknowledgements  
1
4.1 Remember, it’s only a hobby. Most of the issues with FT8 operating are not due to malice but  
ordinary hams like you and me, exploring the mode and picking up tricks as we go. We make  
mistakes. We get things wrong. We experiment. We try. We learn. We enjoy ourselves and help  
each other out. Slack needs to be cut. Stay cool. Chill bro!  
1
4.2 Although my name is on the front, this document is largely the product of the HF DX community.  
Please join me in thanking the numerous amateurs who have kindly contributed ideas, comments  
and tips, particularly of course the professors (Steven Franke, K9AN and Joe Taylor, K1JT) who gave  
us the mode, plus the other WSJT-X developers and long-suffering support crew on the WSJT  
reflectors (Bill Somerville, G4WJS in particular). I have collated, interpreted and expanded upon  
their inputs, drawing heavily on their inspiration and information. I take full responsibility for all  
my mistakes … and express my sincere thanks for those of you who put me straight!  
1
4.3 Your feedback on this document, such as corrections, responses/challenges, improvement  
suggestions and further tips, are very welcome. Please email me: Gary@isect.com I will try to  
maintain the online living version of this document on my website (www.G4iFB.com) as time and  
energy permits. No promises though: I have a job to do and given the choice I’d rather be flapping  
my trusty Bencher paddle than bashing the keyboard.  
I am part of the merry band that developed and  
promotes the DX Code of Conduct. We know it is  
imperfect but the situation would be even worse  
without it! Something had to be done about  
declining operating standards, so we did …  
something. So what have you done lately?  
an stomach any more of my  
catch me on the air  
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Appendix A: About FT8  
A limited amount of technical information about FT8 is available on the web, such as this brief outline  
when FT8 was first announced with the release of WSJT-X v1.8.0 Release Candidate 1 (I have added a few  
links for those who, like me, feel the urge to explore further):  
WSJT-X Version 1.8.0 includes a new mode called FT8, developed by K9AN and K1JT. The mode  
name "FT8" stands for "Franke and Taylor, 8-FSK modulation". FT8 uses 15-second T/R sequences  
and provides 50% or better decoding probability down to -20 dB on an AWGN channel. An auto-  
sequencing facility includes an option to respond automatically to the first decoded reply to your  
CQ. FT8 QSOs are 4 times faster than those made with JT65 or JT9. FT8 is an excellent mode for  
HF DXing and for situations like multi-hop Es on 6 meters, where deep QSB may make fast and  
reliable completion of QSOs desirable.  
Some important characteristics of FT8:  
T/R sequence length: 15 s  
Message length: 75 bits + 12-bit CRC  
FEC code: LDPC (174,87)  
Modulation: 8-FSK, tone spacing 6.25 Hz  
Occupied bandwidth: 50 Hz  
Synchronization: 7x7 Costas arrays at start, middle, and end  
Transmission duration: 79*1920/12000 = 12.64 s  
Decoding threshold: -20 dB; several dB lower with AP decoding  
Multi-decoder finds and decodes all FT8 signals in passband  
Optional auto-sequencing and auto-reply to a CQ response  
Operational behavior similar to JT9, JT65  
Two further definitive sources of information on FT8 are the WSJT-X help file (provided with the program)  
Work the World with WSJT-X, Part 1: Operating Capabilities QST October 2017, pages 30-36  a  
November 2017, pages 34-39 dips further into the mathematics, Forward Error Correction etc.  
An excellent presentation by Joe Taylor explains the history behind WSJT-X and FT8.  
One further source is the source itself, in other words the program source code for WSJT-X and the  
associated documentation, generously made freely available through a Creative Commons license in  
order to encourage widespread uptake and continued development of the digital modes.  
Finally, Joe maintains a set of references at www.physics.princeton.edu/pulsar/K1JT/refs.html  
The popularity of FT8 on HF is largely a happy accident in that it fulfilled a latent  
frustration of many potential users of WSJT-X with the slow rate of QSOs using 1 minute  
T/R periods. Clearly that frustrated group of users did not require the greater sensitivity  
of JT65 or JT9 and once the level activity grew greatly the opportunities for many QSOs,  
even with limited equipment, caused a near exponential growth since launch.”  
[
Bill Somerville, G4WJS]  
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Appendix B: JS8 for weak signal text chat  
JS8 (Jordan Sherer-designed MSK-8) is an experimental digimode inspired by  
FT8 shortly after its release in 2017, designed and then implemented in  
software by developer Jordan Sherer (KN4CRD) during 2018.  
The JS8Call software  
supporting JS8 mode  
was originally known  
as FT8CALL.  
JS8 is derived from FT8 and freely shared in accordance with the FT8 open  
source license, in the best traditions of amateur radio.  
It applies FT8-style message encoding and modulation to longer  
JS8Call has  
a
directed  
messages, in effect allowing senders to transmit across adjacent time  
slots instead of the usual 15 second alternating transmit-receive  
sequence. The tilde character denotes the end of a message sequence.  
calling protocol laid over top  
the base RF transport to  
support free-form and  
directed message passing.  
Hence JS8 + Directed Calling  
7
5-bit JS8 messages cannot be decoded by 77-bit FT8 software. They  
use different sub-bands (e.g. 7078 and 14078 kHz).  
Re the message length, longer” is relative. This is still a block-mode = JS8Call … The mode is: JS8.  
system compressing and sending an entire block of information (several The app is: JS8Call.”  
characters) at a time, unlike say RTTY, PSK or CW where each individual  
character is encoded separately then sent, received and decoded.  
As of JS8Call version 2.1, four speeds are available in JS8:  
Slow: 30 second frames, 25 Hz bandwidth, 3.125 baud (~3½ WPM) decoding down to -28dB.  
Normal: 15 second frames, 50 Hz bandwidth, 6.25 baud (~7½ WPM) decoding down to -24dB.  
Fast: 10 second frames, 80 Hz bandwidth, 10 baud (~12 WPM) decoding down to -20dB.  
Turbo: 6 second frames, 160Hz bandwidth, 20 baud (~24 WPM) decoding down to -18dB.  
The FT8-style message integrity controls built-in to JS8 make it  
suitable for applications such as leisurely chats over weak signal  
paths, emergency comms using solar or wind powered QRP  
stations with temporary/inefficient antennas, and automated  
beacon-type stations broadcasting sensor data. It makes efficient  
use of even low-quality RF bandwidth.  
The idea with JS8Call is to take the  
robustness of FT8 mode and layer  
on a messaging and network  
protocol  
communication on HF with a  
keyboard-to-keyboard interface.  
JS8Call is heavily inspired by WSJT-  
X, Fldigi, and FSQCall and would not  
exist without the hard work and  
dedication of the many developers  
in the amateur radio community.”  
for  
weak  
signal  
For more information, see:  
“JS8Call is a derivative of the WSJT-X application, restructured and  
redesigned for keyboard-to-keyboard message passing.”  
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FT8 Operating Guide  
Appendix C: JTDX  
Personally, I prefer JTDX over WSJT-X for FT8 HF DXing. The programs are similar enough that swapping  
between them is easy with a shallow learning-curve. I find the JTDX user interface more intuitive, less  
awkward and stressful, easier and more efficient in practice than WSJT-X. YMMV.  
The main screen layout  moves the settings to the righthand side leaving more vertical space on  
the left for up to 50 ‘band activity’ decodes, showing most if not all of the decodes from the last  
period even on a very busy HF band. There is less space for messages to/from me in the right ‘Rx  
frequency’ pane but still plenty enough in practice for the present and usually the previous QSO.  
I can left click the waterfall to move the dead green Rx goalposts there, or right click to move the red  
Tx goalposts. That is intuitive and one-handed, with no need to press a keyboard key while clicking  
the mouse.  
We have the option to shift the timestamps to the right of the waterfall or hide them useful as they  
can obscure weak DX fox signals. Also the waterfall sliders have labels and values, making it easier to  
try out changes and if necessary return to known good settings. JTDX is getting even better by the  
week!  
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FT8 Operating Guide  
My even/odd Tx slot setting button is blue or yellow, respectively, and the adjacent clock uses the  
same colours depending on the time, making it easy to determine whether I would be  
transmitting or listening at any point: I transmit when the colours match.  
Having selected ‘Prompt me to log QSO’ under F2 Settings Reporting tab, JTDX displays  
the logging pane at the end of a QSO, waiting patiently for me to check it and click “Log  
QSO”. That click also re-enables Tx and selects Tx 6, my CQ message, making it easier to  
continue CQing, unless I have selected “1 QSO” on the main menu  That’s a single-shot  
option meaning remain in receive after completing the present QSO’. It’s an easy way  
to conclude a session and slip away for a cup of tea.  
If I select ‘Enable automatic logging of QSO’ under F2 Settings  Reporting  my QSOs are logged  
automatically on completion, giving me no chance to check and modify the log entry (e.g. noting the  
power I am using). Even with that option selected, JTDX deliberately does not recommence CQing  
after a QSO is completed and logged, as that would make the operator redundant.  
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FT8 Operating Guide  
When I respond to someone else’s CQ, there is an option to stop my transmissions automatically if  
he responds to someone else … which reduces needless QRM, reduces my power bill and most  
importantly gives me the chance to check that my transmit frequency appears clear when I would  
otherwise have been transmitting. [WSJT-X only stops my simplex transmissions.] If for some reason  
I want to hound someone, calling them repeatedly, I simply click the Hound button … but that setting  
also stops me sending a custom 73 message.  
The PC beeps when people call me, using the Windows default output sound card. A handy audio  
cue, that, if I am busy working on another screen.  
When I am CQing, the auto-sequencer can be  
Better autosequencing is a distinct  
configured to auto-respond to the most distant caller  
advantage of JTDX over WSJT-X for DXers  
instead of simply the first caller decoded. I guess it  
uses grid squares to calculate the distance, otherwise  
the country identified by the prefix. There are other  
autosequence options too.  
like me … but it still makes mistakes, so  
keep an eye on it anyway.  
Using a new control on the waterfall, I can shift the timestamp from the left to the right edge of the  
waterfall, or turn it off completely, making it easier to see feint traces of DX foxes on the left.  
I can easily generate directional CQs targeting a specific country or continent, and more importantly  
the autoresponder can be set to ignore callers not in my target area, if I choose to do so. [I’m not  
sure it handles custom CQs though: it only accepts 1 or 2 letters in the entry box].  
When someone responds to my CQ call but their response decodes late (after I have started my next  
CQ call), the autoresponder automatically flips to sending them their report and erases the partially-  
transmitted CQ message from my screen, making it easier to figure out what messages were sent.  
Logger32 communicates bidirectionally with JTDX 39 via UDP  
After clicking someone’s  
messages. I can display all the stations decoded in JTDX on  
Logger32’s “UDP bandmap”, with any new ones highlighted for me  
in the same colours as DXcluster and RBN spots on the conventional  
bandmaps . If I click a decoded FT8  
callsign  
on the UDP  
bandmap, Logger32 waits  
politely until it has received a  
further message from him  
before telling JTDX to call  
him. With minimal user  
feedback (just a box around  
the call on the bandmap as it  
waits to call the selected  
station), the pregnant pause  
can be disconcerting but be  
patient. Trust me, it works …  
eventually, usually.  
callsign on the UDP bandmap, JTDX  
will call him when appropriate (either  
when he next CQs or when he sends  
his 73 or RR73 message at the end of a  
QSO, according to the bandmap config  
settings). If he doesn’t immediately  
respond to my call, I can simply wait  
patiently to call him again, try calling  
another wanted station in the same  
way, start CQing, or give up.  
39  
It also communicates with WSJT-X via UDP, with minor differences e.g. WSJT-X only lets Logger32 respond to CQs.  
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FT8 Operating Guide  
Logger32 can optionally also display another bandmap-type thing  
showing only the stations currently calling me, with their entries  
highlighted in the normal manner – handy when I’m being called by  
several stations at the same time, trying to decide which one to respond  
to first. In the example  I’m being called by LY1CZ who I have  
contacted before (hence the X) plus DJ0YI in grid JN48 that I haven’t  
worked yet on this band (hence the blue highlighting). While it would be  
good to contact LY1CZ again, I would probably respond to the German  
first by double-clicking a decode from him in the Rx frequency pane on  
JTDX, letting the autosequencer take us through the conventional QSO  
sequence. Meanwhile, if anyone else calls me during our QSO, their call  
will also appear as if by magic on the calling me bandmap so I can get  
ready to respond to one of the callers in the same manner  going for  
the highlighted ones first, generally.  
The JTDX lower status line shows useful info. It pays to keep an eye on things. Here are three  
snapshots showing the 8 fields at different stages of a QSO ▼  
1
2
This field normally shows the message you are transmitting (yellow) or ‘Receiving’ (green). The red  
warning message appears when the watchdog counts down to zero and your transmissions have  
ceased.  
If you are monitoring an active FT8 subband and  
see plenty of FT8 signal blobs on the waterfall  
but no decodes, check that you haven’t  
accidentally selected a different mode. Doh!  
The mode: JTDX supports FT8 and a few other  
HF JT-type digimodes (JT9 & JT65, T10 and  
WSPR-2 ).  
3
4
The message you transmitted last.  
Watchdog timer counting down the minutes remaining. Click anywhere in the program’s main  
window, or log a QSO, to reset it to the starting value defined in F2 Settings  General tab.  
5
6
Shows each over ticking away the 15 seconds with a coloured progress bar. Red = transmitting.  
Green = receiving.  
The callsign of the station logged most recently. Handy if, like me, you sometimes get distracted and  
forget whether you have logged someone.  
7
8
The date in UTC (I presume).  
How many QSOs you have logged on this mode, in this program, under your current callsign, in the  
current ADIF log file.  
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FT8 Operating Guide  
JTDX supports contacting foxes with a simple click or right-click on the Hound button on the main  
screen  Left-click the  
button to make brief  
split QSOs without  
QSYing below 1000 Hz  
(
e.g. when working a  
DX station using  
MSHV’s multi-transmit  
function), then right-  
click if you want your  
rig to QSY below 1000  
automatically  
the DX responds to you  
the button then shows HoundFC meaning hound with  
Frequency Control). The auto-QSY function is disabled and  
cannot be selected on the normal FT8 frequencies since DX  
stations should not be using fox-n-hounds or indeed multi-  
transmit mode in the normal FT8 subbands.  
when  
(
Pileups clog-up the normal subband.  
Spare a thought for those who are  
not presently trying to work the DX.  
Please take your pileup elsewhere!  
The Hound button also lets us hound (as in pester) DX  
stations, calling them persistently even as they call and contact other stations. There are situations  
where that may be justified, but please consider the effect continuous calling has both on the DX and  
on other band users. If your calls are going unheeded, it may be that your Tx frequency is busy at the  
DX end. If you are so selfish as to be calling the DX simplex, your calls may well cause QRM to the  
stations he is calling and working. Play nicely, please.  
Ever wondered about the little  
symbols that appear in some  
decodes?  
In JTDX, the symbols  
between the audio frequency and the  
decodes message denotes the specific  
digimode: a tilde (~) means FT8, and a  
colon (:) means FT4. Here  I was on  
FT8 until 00:09:06, then I changed to  
FT4 … I guess there are other symbols  
for the other digimodes but you’ll  
have to figure them out for yourself.  
The ‘help’ for JTDX is vestigial and 2  
years out of date so it took some  
Googling and checking to figure this  
much out about the symbols. It’s a  
never-ending challenge to document  
this stuff!  
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FT8 Operating Guide  
There are more symbols at the left edge of the country area of the  
band activity window . I think a solid (filled) bullet point means the  
sender is on LoTW; an asterisk means decoding used a hint i.e. a priori  
info from previous messages; an empty (unfilled) bullet means it used  
a hint and the user is on LoTW; no symbol presumably means he’s  
neither a LoTW user nor was a hint used … but I’m not entirely sure  
about this.  
In WSJT-X, the symbols may differ. It’s left as an exercise  
for you, dear reader, to figure out what they all mean.  
There are fewer bugs and flaws in JTDX than WSJT-X but some issues remain e.g.:  
In an early version, the main screen’s radio message-selector buttons used to be clickable during a  
transmission, allowing us to select the next message after the present one is gone, manually  
overriding the autosequencer. For some reason, that handy trick no longer works. We can still click  
the Tx buttons to send a given message now, but if we do that during a transmission, it changes the  
message currently being sent which can easily result in a corrupted, undecodable message unless we  
are careful/lucky with the timing.  
During QSOs, JTDX quite often replaces my manually-typed custom 73 message with the boring auto-  
generated default (<his call> <my call> 73), too late for me to re-type the message I wanted to send.  
This usually happens when the autosequencer has to repeat a message, so I guess it is an annoying  
little featurein the autosequence logic.  
Unless my custom Tx 5 message includes the magic string “73”, the QSO is not automatically logged,  
nor am I prompted to log it. It just quietly disappears into the ether.  
If I fiddle with the settings using F2, when I exit the settings my transmission is aborted and the callsign  
of whoever I’m working is cleared. Too bad. Unless I remember their callsign they’re toast.  
Selecting or deselecting the RRR message during a QSO doesn’t simply change the contents of Tx 4 as  
expected: it also appears to select a different message to send next, for no apparent reason, but  
luckily the autosequencer generally picks the correct one anyway.  
With Hound selected in order to hound a selected DX station, double-clicking a decoded message  
from someone else has no effect. I think this may be intentional  it’s certainly a handy reminder to  
deselect Hound.  
Also, while in Hound mode, we can’t send custom 73 messages. I accept that the primary reason for  
fox-n-hounds is to make QSOs as efficiently as possible so 73 messages are superfluous but  
occasionally there are genuine reasons for hounds to want to send custom messages to the fox  for  
example “LONG PATH”, “TRY CW”, “ZL CALLING”, “CHK SMS” or <ahem> “WHEN 160”. The  
workaround is simply to deselect Hound mode.  
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FT8 Operating Guide  
Appendix D: FT8 under the hood  
FT8 does not simply encode and transmit our messages character-by-character (in the same way as, say,  
CW or RTTY or PSK). The entire message is encoded first, as a block, using a clever algorithm that  
compresses the message down to 77 bits which are then transmitted  
digitally along with error correction bits through our radios and the FT4 transmits the same 77-bit  
ether, taking 12.6 seconds. On the receiving end, the process happens messages  
plus  
error  
in reverse: the digital bits are dragged kicking-and-screaming from the correction bits at roughly  
ether, error-corrected then expanded back into those human- twice the rate and bandwidth  
readable and often actionable message that we read and double-click  which halves the sensitivity  
on  hopefully within the remaining 2.4 seconds before the next (-3.2 dB in fact).  
transmission period begins.  
The ‘compression down to 77 bits’ on transmit, and corresponding expansion on receive, introduces hard  
constraints on the amount and nature of information that can be passed using FT8. Under the covers, the  
software uses algorithms for compression and expansion, algorithms that are specified as an integral part  
of the FT8 protocol. They are designed to work in a fixed, predefined, mechanistic (=algorithmic!) way,  
squeezing as much useful information as possible into the few bits exchanged in each over. In order to  
do that, they make some simplifications which, in turn, create the constraints that we live with.  
Each character in a 13-character free message is converted  
to a number, then those numbers are multiplied together  
forming a large integer of 71 binary bits. Standard messages  
consist of two 28-bit fields normally used for callsigns and a  
Steve Franke, Bill Somerville and Joe  
Taylor in QEX July/August 2020.  
1
5-bit field for a grid locator, report, acknowledgment, or  
73” message, also totalling 71 bits. Six message-type bits  
are appended, giving 77 bits. These are the precious  
information payload. All the remaining bits in transmitted  
FT8 and FT4 messages are required for error-correction  
purposes, enabling the payload to be reliably communicated  
over a noisy radio channel. The Low Density Parity Check is  
assembled thus:  
A 14-bit Cyclic Redundancy Check is calculated on the 77  
bits and appended, giving 91 bits.  
Next an 83-bit parity code is calculated and appended,  
giving 174 bits.  
The 174 bits are grouped into 58 chunks of three bits  
each, which are then Gray coded.  
Symbols are now assembled from a 7-chunk Costas array +  
the first 29 Gray-coded chunks + the 7 Costas + the  
remaining 29 Gray-coded chunks + the 7 Costas, resulting in  
7
9 symbols for transmission. Those Costas arrays (“sync  
vectors”) sent at the start, middle and end of each FT8  
message are used to synchronize the receiver to the sender  
such that bits can be reliably timed within the transmissions.  
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FT8 Operating Guide  
Notice there are just 28 bits available to communicate a conventional callsign. 28 bits gives 2 (the 28  
power of 2) possible values, which in decimal means a little under 270 million possible callsigns. Using  
the algorithm defined in the protocol, that is more than sufficient  
to code all the normal, conventional, old-style, everyday, standard 9LY1JM was a classic example  an  
callsigns currently in use across the world, each one coding to a unusual callsign allocated for a  
unique digital value … but 28 bits is not enough for all the weird DXpedition. That “Y” in the prefix  
and wonderful special event calls that are increasingly issued. The meant it would not fit into the 28  
prefix parts of our calls are defined quite narrowly in the ITU bits allowed for a conventional call  
regulations and by general convention, but the suffix parts are without being hashed …. but bugs  
more flexible, giving too many possibilities to squeeze into the in the autosequencing in WSJT-X  
available 28 bits. Any HF DXer will surely have come across some messed up the fox-and-hounds  
of them on air, on the legacy modes  VK novice calls, for example, DXpedition protocol with a hashed  
have 4-character suffixes starting with “F”. Self-assigned suffixes callsign. Live-n-learn.  
are another example: when they were first used on-air, many of us  
wondered whether /LH indicated the lighthouse stations were actually in Norway! I’ve worked and logged  
stations using /QRP, /MM, /M, /P, /A, /AM, /PP, /R and other curious variants, some made up on the spot,  
some probably not in conformance with the op’s license, as well as the location-variant suffixes such as  
/
VE2 and CEPT prefixes such as P4/.  
The same consideration applies to the 4-character  
Maidenhead grid squares communicated with 15 digital  
bits. 15 bits is more than adequate for grid square  
references comprised of two Latin letters and two decimal  
digits but is not enough to code all possible combinations  
of four letters or numerals, which would require at least  
Clearly, there’s a lot of processing going  
on when FT8 signals are received and  
reasonably fast  
decoded hence  
a
computer is needed. It’s not just the raw  
CPU speed that matters though, as the  
captured audio is written to disk before  
processing: a slow disk, or contention  
caused by other software such as antivirus  
and backup programs, can cause delays  
that result in no decodes being displayed  
after some if not all overs. Network delays  
may also cause problems e.g. if you elect  
3
2
6x36x36x36 values or 1,679,616 in decimal, more than  
20  
… in other words FT8 falls 3 bits short. That said, the  
particular grid RR73 is exceptionally interpreted by the  
software as a message, not a grid. If an intrepid sailor ever  
activates that grid square on FT8, things could get  
interesting.  
6
Six message-type bits cater for 2 (decimal 64) distinct to send decodes to PSK Reporter.  
types of message. Currently, the following message types  
are in use:  
1
2
3
4
5
6
7
8
9
. Tx1 initial call with 4-character grid locator e.g. K1JT ZL2IFB RF80  
. Tx2 response to a caller with signed 2-digit signal report e.g. K1JT ZL2IFB -05  
. Tx3 acknowledging the received report and returning one e.g. K1JT ZL2IFB R-05  
. Tx4 all received message e.g. K1JT ZL2IFB RRR  
. Tx5 free text message, normally a 73 e.g. K1JT ZL2IFB 73  
. Tx6 CQ message e.g. CQ ZL2IFB RF80  
. Message contains a hashed non-standard callsign  
. NA VHF contest exchange  
. EU VHF contest exchange  
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1
1
1
1
1
0. ARRL RTTY Roundup exchange  
1. ARRL Field Day exchange  
There are enough bits for 51  
additional message types.  
Contact Joe Taylor and team if  
you intend to define and use  
additional message types.  
2. DXpedition (fox-n-hounds) mode  
3. Telemetry: the 71-bit payload contains arbitrary data  
4-64. Not currently used  ►  
The FT8 modulation scheme is 8-FSK i.e. an 8-bit transmission using 8 different audio tones separated by  
just 6.25 Hz, giving an overall transmission bandwidth under optimal conditions of 50 Hz.  
FSK in general is chosen because it allows the use of constant  
FT8 uses Gaussian FSK (GFSK).  
Rather than sharp transitions  
between FSK tones, Gaussian  
shaping is applied to smooth  
the transitions, reducing  
unwanted sidebands bringing  
the signal closer to the  
amplitude and near continuous phase signals, as such linear RF  
stages are not necessary this making virtually any transmitter  
suitable. FSK signals are inherently narrow without having to  
apply complicated pre-modulation filtering. They are also  
relatively easy to analyse in the frequency domain within a  
decoder routine. Basic characteristics that have to be designed  
are bandwidth (increases with greater N in N-FSK) vs. higher  
symbol rates (increases with greater N in N-FSK). Given the typical  
frequency stability and propagation stability on the bands  
targeted, 8-FSK turns out to be a good choice for a modulation  
bandwidth around 50 Hz for 15s T/R periods and the alphabet, and  
symbol rate required for WSJT-X style QSO messages plus parity  
optimal bandwidth.  
The  
amount of smoothing trades-  
off narrower transmitted  
bandwidth against reduced  
decodability.  
Plain FSK and even GFSK are  
Given the decoded message we regenerate the transmitted  
straightforward  
and  
waveform and use that as a reference to derive the time-varying,  
complex, gain function that describes the channel. We use this to  
reconstruct a (nearly) noiseless version of the received signal’s  
waveform that includes the channel-induced amplitude fading and  
phase-variation. The reconstructed signal is subtracted from the  
received data, enabling us to uncover weaker signals that occupy the  
same frequency slot as the subtracted strong signal. These weaker  
signals can often be decoded on a second decoding pass, after the  
stronger signals have been subtracted.” [Steve Franke, K9AN]  
conventional: what makes  
FT8 special is the clever way  
the  
software  
makes  
additional passes through the  
captured  
mathematically  
audio,  
removing  
reconstructed signals a layer  
at a time to reveal weaker  
signals beneath  Cunning!  
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Appendix E: FT8 logging and lookups  
WSJT-X and derivative programs log QSOs using the ADIF XML standard. Almost all logging software can  
import ADIF log files, hence it is possible to merge your digimode QSOs made and logged in WSJT-X etc.  
with your legacy mode QSOs logged in programs such as Logger32, Ham Radio Deluxe, AClog, Log4OM,  
DXlab, N1MM+ and many others including online logs such as LoTW, QRZ.com and eQSL, by importing the  
ADIF. However, there are drawbacks to this approach:  
A few logging programs make a hash of importing ADIF files, for example misinterpreting some of the  
standard fields. Fortunately, this is a rare problem, and the basic QSO data (at least) generally makes  
it through unscathed. Issues tend to arise whenever new ADIF standards are implemented, as it takes  
time and effort to interpret the standard and update the software accordingly.  
Importing an ADIF log is generally a manual, asynchronous activity: we have to stop logging digimode  
QSOs for a while, open the logging program, run the ADIF import function to update our log, deal  
with any options and errors, and then resume our digimode activities.  
It is error-prone e.g. forgetting to do the import, importing into different logs by mistake, and  
importing the same ADIF file into the same log more than once, potentially creating duplicate log  
entries (unless the logging program ADIF import function automatically spots and skips dupes).  
Real-time log updating is a better approach, where capable logging programs receive and merge digimode  
QSO details broadcast by WSJT-X or JTDX as TCP or UDP network datagrams whenever we complete and  
log an FT8 QSO.  
Tighter integration of the digimode and logging software extends the possibilities. Bidirectional UDP  
connections between the digimode engine and logging program make it possible, for example, to lookup  
any previously-logged QSOs with a station we are contacting on FT8, showing details such as the  
operator’s name and QTH, perhaps displaying their QRZ.com page and email address for good measure.  
For DXers, it enables “new ones” to be highlighted as they appear on the decodes, according to how we  
define “new ones” e.g. new grids, DXCC countries, zones, prefixes, club members, LoTW users, states etc.,  
either all-time, just this year or month or contest, just on this band or mode, other criteria, or some  
combination of the above.  
WSJT-X is unlikely ever to be developed into a fully-fledged logging and awards-tracking program: the  
team’s prime focus is on the coding, communication and decoding of weak signals using various  
digimodes, not logging  and fair enough, they are doing a great job with that. More likely is that logging  
programs will be adapted to do the digimode stuff, perhaps calling on WSJT-X or the coding and decoding  
engines to do so in much the same way that some logging programs already call MMVARI or MMTTY,  
through their own internal program functions, or using shared library functions to implement an FT8  
modem.  
Meanwhile, enterprising programmers have developed utilities  
to plug some of the gaps, with JTalert being top of the heap.  
JTalert uses the decodes and logged QSOs from WSJT-X to  
highlight new ones (maintaining an internal HamApps database)  
and pass logged QSOs through to other logging programs. It acts  
as a middle-man with benefits.  
I gather that JTalert can pass each  
FT8 QSO as it is logged in WSJT or  
JTDX to DXkeeper which can, in  
turn, send on the info automatically  
to TQSL to update LoTW. Cool!  
To upload your FT8 QSOs to LoTW you need the TQSL program along with a digital certificate, both from  
ARRL, confirming that you are duly licensed to use your callsign. If you don’t already have those, start  
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The minimalist approach is to use the logging  
The ADIF log file grows bigger with each new QSO  
but TQSL maintains its own internal list of QSOs  
previously signed and uploaded, and by default it  
automatically skips those QSOs, only signing and  
uploading any new ones since the last  
run. Therefore, there’s no need to worry about  
separating out the recent QSOs: simply pass the  
entire ADIF through TQSL each time. The whole  
process is painless and typically takes less than a  
minute. You’ll soon get the hang of it.  
facility built-in to WSJT-X (or JTDX or MSHV or  
whatever): when you complete and log an FT8  
contact, it appends a QSO record to the  
wsjtx_log.adi (ADIF) file in the directory  
%LocalAppData%\WSJT-X. You can sign and  
upload that ADIF file to LoTW manually using TQSL  
as often as you like: as an active DXer I sign and  
upload the latest QSOs once or twice a day, others  
may do it weekly, monthly or ‘whenever’.  
If you use one or more separate logging programs,  
it’s a good idea to pull all your QSOs (on FT8, JT9, CW, SSB or whatever, made by regular DXing or  
contesting) into one consolidated log, then generate, sign and upload an ADIF file from the logging  
program. Having one consolidated log makes it simpler to search for all previous QSOs with someone,  
and generate statistics such as the total number of DXCC countries you have worked. Most logging  
programs also let you download and save the confirmations from LoTW and input details of any QSL cards  
you receive, updating the relevant QSOs to show they have been confirmed. When you have enough  
confirmations, you can apply for awards such as DXCC.  
JTSummary was 40 a handy  
little utility by Aki JA1NLX that  
analysed an ADIF log to  
determine the number of QSOs  
made and confirmed on various  
modes.  
Of the ~118k QSOs in my log, I’ve  
made ~33k FT8 QSOs in over 230  
DXCC countries. Nearly three-  
quarters of the FT8 QSOs are  
confirmed, compared to about  
6
0% of my CW and SSB QSOs.  
Digimode QSOs require  
a
computer, hence it is more likely  
that digimode QSOs will be  
logged and confirmed on LoTW  
than legacy mode QSOs.  
JTSummary also let me graph  
the digimode statistics by bands,  
modes and continents. Neat!  
Thanks Aki!  
40  
JTsummary is no longer supported by Aki but Google may find you a copy online: look for the last version 1.28.  
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Appendix F: Contesting with WSJT-X  
Both FT8 and FT4 can be used to exchange (some) contest information such as  
sections and serial numbers using specific message types, in addition to the normal  
QSO information. Contest organizers may allow or disallow FT4 and FT8 in their  
events, possibly defining separate categories: check the rules!  
JTDX does not  
yet] support  
FT8 contesting  
[
To enable contest mode  
in WSJT-X, go to F2  
Settings Advanced,  
select  
the  
Special  
operating activity then  
select the relevant (or  
closest available!) contest  
type .  
Enter the  
exchange you should be  
sending e.g. your field day  
section code or ‘DX’. This  
text is automatically  
included in your outgoing  
exchange message, and is  
logged on receipt from  
other participants.  
Talking of logging, in  
contest mode WSJT-X  
generates  
a plaintext  
column-aligned Cabrillo  
format contest log in  
addition to the usual  
ADIF log and UDP or TCP  
broadcasts onto your  
shack network … which  
in turn enables contesting software such as N1MM+ to support FT8 contests, with all the advantages of  
multiplier tracking and dupe-checking etc.  
Check the contest rules for suggested or permitted  
frequencies. It’s a good idea to define them in WSJT-  
X’s frequencies table so they appear on the band  
selector.  
If you set up a separate WSJT-X configuration for  
contesting, you’ll avoid cluttering-up your normal  
everyday settings. You can preload a specific  
configuration when launching WSJT-X using the -c  
command line parameter (see the F1 help for  
details), or simply select it from the menu which  
closes and relaunches the program for you.  
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In contest mode, the main WSJT-X window and operation is the same as always, with selector buttons for  
the next message and Enable Tx to start transmitting on the next applicable slot ▼  
All the usual FT8 operating and avoidance tactics apply to contests:  
Watch and if necessary adjust your audio levels on receive and transmit to stay in  
the green zone, avoiding the red.  
Use the  
normal FT8  
subbbands,  
other modes  
or the WARC  
bands to  
avoid FT8  
and FT4  
contests.  
Try not to transmit on a busy frequency.  
Keep your power down to avoid causing receiver overload and nasty red blobs on  
waterfalls at the other end.  
Chase down bonus points or multipliers according to the contest rules, avoiding  
disappointment.  
Study and comply with the contest rules to avoid disqualification.  
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FT8 Operating Guide  
Appendix G: Picking FT8 cherries with Logger32  
Most of the time, there are plenty of stations active on FT8 on the bands I’m using. With my ZL prefix, I  
seldom need to CQ for long before someone responds  and that suits me fine. Sometimes, though, when  
my CQs are going unheeded, it’s time to change tactics by picking out and calling other stations.  
4
1
So who shall I call? As an HF DXer, these are my priorities from the top down :  
An All -Time New One i.e. a DXCC country that I have never worked before, not ever on any band or  
mode. For me, these are the ripest, reddest, sweetest, most ‘needed’ cherries of all, and as such I’m  
willing to invest a lot of effort to pluck them.  
A DXCC country that I have worked before but don’t yet have confirmed on any band or mode.  
A new DXCC country for me on this band.  
Someone I have just contacted and logged (are they calling back to correct something, tell me  
something or still trying to complete the QSO?).  
A new DXCC country on any digimode.  
A new DXCC country on FT8.  
A DXCC country that I have worked before but don’t yet have confirmed on this band.  
A DXCC country that I have worked before but don’t yet have confirmed on any digimode.  
A DXCC country that I have worked before but don’t yet have confirmed on FT8.  
An old friend whose callsign I recognise, especially if we haven’t caught up in a while.  
A DXpedition to some exotic part of the world, especially to a rare zone or grid.  
An IOTA, SOTA, WFF or special event station that catches my eye e.g. a new IOTA for me.  
Anyone on the Far Side, or who I think might be coming in via the long path.  
Any other IOTA, SOTA or special event station.  
A QRPer or anyone with a weak trace on the waterfall and low signal-to-noise metric.  
Any novice or foundation-class newbie callsign that I recognise as such.  
Anyone with an unusual prefix or suffix.  
Those who call me off-frequency/split, avoiding the unsightly simplex red blob.  
Anyone else. Anyone at all, including people I have worked several times already (within reason!).  
That’s a lot to figure out, in a hurry, when I’m scanning through each batch of decoded message, but  
luckily help is at hand. For a start WSJT-X and JTDX can highlight new ones on FT8 as a result of reading  
their ADIF log files into memory as either program launches. The highlighting is basic and easily messed  
up by me carelessly renaming or deleting the ADIF files, or meddling with the colours.  
I believe JTAlert improves the highlighting … but I don’t use it so that’s all I have to say on that. Sorry.  
Logging programs that interoperate with WSJT-X or JTDX increase the possibilities, for example  
distinguishing ATNOs (All Time New Ones) from those we have worked on other modes, not yet on FT8,  
and determine whether previously-logged QSOs have or have not been confirmed and verified for award  
41  
Your priorities are probably different to mine. I’m listing mine simply to point out the complexity involved, not to claim that  
my priorities are any better than yours. We’re all individual, a.k.a. ‘special’.  
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purposes. Logger32 by Bob K4CY, for example, can display a “UDP BandMap” conceptually and graphically  
similar to Logger32’s bandmaps for DXcluster and RBN DX spots, showing  
callsigns decoded on FT8  The bold red callsigns are stations who have  
called CQ, while the timid blue ones have responded to others’ CQ calls.  
Grid squares sent by some of the stations are highlighted with background  
colours according to whether they are new ones.  
Logger32 gives us  
lots of options to  
customize the  
highlighting rules and  
colours, using  
Config/Appearance  
/
Highlight colours on  
the UDP bandmap  
top line menu.  
Your system will of  
course look different  
to these example  
images unless you  
happen to choose  
the same options  
and colours as me.  
Logger32 supports semi-automatic DXing: we can select interesting stations  
on the UDP band map, then sit back and watch developments. If our chosen  
station completes a QSO or calls CQ, Logger32 sends a UDP message telling  
WSJT-X or JTDX to call him. If he starts another QSO with someone else,  
Logger32 quietly bides its time until it is appropriate to give him another  
call … like this  
When I first  
noticed HL5FUA  
CQing, was  
I
busy with a QSO  
and missed my  
chance  
to  
respond to him.  
Having finished  
my QSO,  
I
clicked to select  
him on the UDP  
band map and  
watched as my  
system  
tail-  
ended him. He  
worked someone else so my system waited then tail-ended him again.  
Bingo! It worked! We QSOd!  
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Logger32 also offers a full-auto “cherry-picking” function – an FT8 automaton or robot that:  
Identifies cherries i.e. potentially interesting stations on the UDP bandmap, according to the  
program’s internal logic and priorities.  
Looks them up in our log and shows any previously-logged QSO information (e.g. date, time, band,  
mode, operator name, QTH, QSL status etc.), plus their country, beam heading etc. as if we had  
entered them manually into the logging pane.  
Looks them up in callsign databases such HamQTH.com or QRZ.com, showing the relevant records.  
At the right moment, sends a UDP message telling WSJT-X or JTDX to call them on FT8.  
Tracks the sequence of messages to determine whether the station responds to us and completes  
the QSO, or else gives up calling after a few goes to wait for the next cherry to ripen.  
It’s up to us whether to use the full-auto cherry-picker function at all, and if so how to configure it. As a  
traditional DXer (=old fart), I prefer to control my station, only making QSOs while physically present in  
the shack, or possibly while at a remote operating position.  
If you are excited at the prospect of letting your PC do all the work, robotically driving up your digimode  
counts for you, knock yourself out (literally if you wish, subject to your licensing laws about being the  
control operator for your station). Just be aware that DXCC rule 6(a) requires “contemporaneous direct  
initiation by the operator on both sides of the contact”.  
If robot-style full-auto is not for you, or if the  
rather cryptic who-to-call-now rules built-in to  
Logger32 don’t reflect your DXing priorities,  
consider the semi-auto option. Choose your  
own cherries: turn off the robot then manually  
click callsigns on Logger32’s UDP bandmap, any  
of those highlit calls being prime candidates.  
Logger32 will then do its level best to prod JTDX  
into working the selected stations  
Trust me, it pays to keep an eye on things, even if  
the robot is running. In particular, make sure your  
receive and transmit audio levels remain in the  
green. It’s down to you to choose your band and  
transmit frequency, to select the best antennas and  
turn the beam to exploit useful propagation paths,  
and to know when to switch to DXpedition mode or  
chase some rare DX that may not be around for  
long. DXing takes skills that are hard to automate.  
Failing that, ignore Logger32’s suggestions  
In addition to practical and technical  
constraints, there are design flaws  
and bugs in the software.  
Sometimes the sequencing fails so  
you need to step in and take charge  
to rescue or abandon failing QSOs.  
entirely: simply double-click the WSJT-X or JTDX decodes from  
stations that catch your beady eye to have the programs call  
them in the old-fashioned manual form of digital DXing.  
Or just CQ and wait for the cherries to fall into your lap  your  
lap, your choice.  
Watching the robot make QSOs is vaguely interesting at first but Contrary to some naysayers, you  
soon becomes dull, compared to the thrill of DXing. Personally, can’t simply wander away and come  
I find I can work DX more efficiently and more effectively than back later to collect your awards –  
the robot … but the robot wins in terms of chair-time. It can do and anyway, that’s no fun and no  
fairly well through sheer persistence. I find it useful, sometimes, achievement for any self-respecting  
to unleash but keep a close eye on the robot while I’m busy DXer. You might as well try DXing via  
doing other things in the shack such as working  or updating SMS TXT messages or email!  
this guide on the adjacent monitor. YMMV.  
In due course, I expect there will be (more) calls to outlaw fully-automated amateur stations except for  
specific, legitimate purposes such as beacons, Skimmers, propagation pingers and the like. That, in turn,  
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may stimulate efforts to ‘out’ the robots  
The team that invented and released FT8 is adamant  
that it should not be fully automated. Fully-automated  
operation has some potentially useful applications  
such as propagation monitoring and remote sensing,  
but for regular DXing most hams agree that full  
automation is unnecessary, inappropriate and  
unethical, filling the bands with junk, cheating regular  
entrants in DX awards and contests, and generally  
devaluing the hobby. Frankly, it’s boring and pointless,  
not in the spirit of amateur radio.  
among us, an interesting challenge in its own  
right, the radio amateursversion of the  
For now, full-auto lights-out robotic FT8  
stations are fairly easy to spot thanks to  
obvious clues such as:  
Operating 24x7, or at least for extended  
periods whereas most normal people  
would need or choose to take breaks.  
Always using auto-sequencing with standard messages  no friendly greetings or off-the-cuff  
comments and responses during or at the end of their QSOs, easily confused by out-sequence-of and  
custom messages.  
Static audio frequency for all transmissions no QSYing to avoid QRM.  
Absence from DXpedition fox-n-hounds pileups.  
Frank admissions by their operators, or at least evasive or dubious answers if challenged about this.  
Stealthier, more sophisticated robots, though, could prove difficult to identify as such and might  
conceivably match competent DXers and contesters in capability.  
Once the robots can work DX, solve catchpas and write user guides as quirky as this one, my days as a  
radio ham and tech author will be over. I can sit on the sidelines watching what remains of my life pass  
me by, quietly humming imaginary Morse QSOs with myself, rocking and dribbling.  
Be especially wary of leaving the robot operating your station unattended for more than just the odd  
moment. Aside from the ethical considerations, practical constraints and bugs, unattended  
operation may be prohibited by your license terms and conditions. Furthermore, there are safety  
hazards. What if faulty equipment leads to overheating and fire? What if someone wanders into the  
shack and fiddles with the controls or touches exposed terminals? What if your system goes haywire,  
causing chaos and confusion on air, perhaps QRMing the emergency services? Your reputation will  
be shot to pieces and the authorities may come a-knocking at your door.  
Fools rush in where  
angels fear to tread  
[
Alexander Pope]  
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Appendix H: FT4, a digimode for contesting  
QSOs”. The software and protocol were refined, then WSJT-X v2.1 was released in July with the following  
specifications:  
4 FSK tones spaced ~20 Hz apart instead of 8 tones ~6 Hz apart,  
hence FT4 vs. FT8 the clue is in the name.  
Lowest copiable  
signal-to-noise ratios  
in 2.5 kHz bandwidth  
SSB +10ish dB  
MSK144 -8 dB  
CW -15 dB  
Small bandwidth (80 Hz) constant-envelope MFSK signals with  
Gaussian smoothing (“GFSK”) giving narrow sidebands (pencil  
skirts) hence room for more thirsty contesters around each FT4  
watering-hole (see next page ►►).  
~21 baud transmission rate and short overs (just 7½ seconds long  
including the couple of seconds needed for decoding) giving quick  
QSOs and a max contest run rate of about 100 QSOs per hour, even  
without the multi-transmit fox-n-hounds DXpedition approach.  
FT4 -17½ dB  
FT8 -21 dB  
JT4 -23 dB  
JT65 -25 dB  
JT9 -27 dB  
Structured messages the same as FT8 using the same encoding  
scheme with 77 payload bits and LDPC (174,91).  
QRA64 -27 dB  
WSPR -31 dB  
Reasonable sensitivity, better than legacy modes but 3½ dB worse  
than FT8 ►  
??  
-35 dB*  
Overs are synchronized needing system clocks accurate to within  
one second (between one second slow and one second fast).  
*
Joe & team are  
developing a new ultra-  
sensitive but very slow  
UDP and TCP links to contest logging software such as N1MM+.  
mode for VLF experimenters  
4
2
For more on FT4, watch these excellent presentations by Joe .  
FT4 is a special-purpose mode designed for rapid-fire contest QSOs. It serves this purpose  
very effectively, but like FT8 the mode is not useful for more extensive conversations. FT4  
uses much less bandwidth than RTTY and provides reliable decoding at much lower signal  
levels. It has no need for “Super Check Partial” or similar contesting aids, and skilled  
operators using FT4 will find less motivation to use a DX Cluster or other non-radio aids. All  
information necessary to score well in a contest can be obtained over the air, during the  
contest, through one’s own antennas and radios.”  
Joe Taylor, April 2019  
42  
The asynchronous timing approach mentioned in an early seminar was abandoned.  
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FT8 Operating Guide  
By smoothing the frequency transitions, GFSK significantly reduces the skirts (sidebands)  
on the two simulated signals shown on the right of this spectrum plot  
narrowing the FT8 bandwidth by a remarkable ~80% at the -80 dB level ▼  
Even unsmoothed, FT4 and FT8 sigs are much narrower than RTTY.  
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FT8 Operating Guide  
That’s it from me,  
It’s time for tea.  
Go work DX,  
I’m QRT!  
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